Effects of Biosolids on Tall Fescue-Kentucky Bluegrass Sod ... · Tall Fescue-Kentucky bluegrass...

Effects of Biosolids on Tall Fescue-Kentucky Bluegrass Sod Production and

Soil Chemical and Physical Properties

Joseph Cataldi

Thesis submitted to the faculty of the Virginia Polytechnic Institute and State University in

partial fulfillment of the requirements for the degree of

Masters of Science

in

Crop and Soil Environmental Sciences

Erik H. Ervin, chair

Gregory K. Evanylo

J. Michael Goatley Jr.

May 8, 2013

Blacksburg, VA

Keywords: Biosolids, turfgrass, sod production, plant available nitrogen, phosphorus

accumulation, mineral matter export

Effects of Biosolids on Tall Fescue-Kentucky Bluegrass Sod Production and Soil Chemical

and Physical Properties

Derik Cataldi

Abstract

Composted biosolids have been shown to enhance turfgrass establishment and growth

more than fertilizer alone, but few studies have investigated the production of turfgrass using

uncomposted biosolids. Increasingly employed treatment methods that generate pathogen-free,

low pollutant-containing biosolids are creating alternative products for use in urban settings.

Understanding the effects of these uncomposted and alternative biosolids products on turfgrass

culture and soil chemical and physical properties is essential to understanding the benefits these

products may provide in sod production systems. The objectives of this study were to compare

processing methods, application and N mineralization rates of two biosolids products and an

inorganic fertilizer control for sod fertilization on 1) agronomic parameters related to turfgrass

quality, 2) the amount of soil, C and P exported at harvest, and 3) chemical and physical

properties of the soil following sod harvest as an indicator of the benefits of biosolids use. The

study was conducted on a sod farm in Remington, Virginia on a silt loam Ashburn-Dulles

complex from 2009 to 2012. The biosolids products were applied at estimated plant available

nitrogen (PAN) rates of 98 kg N ha-1 (0.5X), 196 kg N ha-1 (1.0X) and 294 kg N ha-1 (1.5X) for

a tall fescue (Festuca arundinacea Schreb. ‘Rebel Exeda’ ‘Rebel IV’ and ‘Justice’)/ Kentucky

bluegrass (Poa pratensis L. ‘Midnight’) mixture. One biosolids product was an anaerobically

digested dewatered cake applied at 15, 30.5 and 46 wet Mg ha-1. The second biosolids product

was the same cake blended with wood fines applied at 17, 34 and 51 wet Mg ha-1. The biosolids

treatments were compared to an inorganic fertilizer control that supplied 196 kg N ha-1 through

three applications over the production cycle. There were no differences in establishment between

the cake biosolids treatments and the inorganic fertilizer control, but all of the blended biosolids

were slower to establish. Only the 1.0X and 1.5X PAN rates from the cake biosolids matched the

inorganic fertilizer control in producing an acceptable quality sod in ten months. Lower nitrogen

uptake between the blended biosolids treatments compared to the inorganic fertilizer control and

lower although acceptable sod quality ratings at harvest of the 1.0X cake biosolids indicate our

PAN estimates of 30% organic nitrogen mineralization overestimated the PAN for both

materials. There were no differences in sod tensile strength between the 1.5X cake biosolids and

inorganic fertilizer control. There were no differences in transplant rooting strength among all

treatments. After repeat applications of biosolids, the 0.5X rates did not increase soil extractable

phosphorus, while the 1.0X rates steadily increased soil extractable phosphorus at. The 1.0X and

1.5X biosolids rates increased soil organic matter content, but only the 1.5X rate of cake

biosolids reduced soil bulk density and mineral matter export at harvest. Overall results indicate

that the cake biosolids are an acceptable fertility alternative to inorganic fertilizer, and

applications of biosolids for sod production can improve soil quality. Sod growers should

consider using biosolids in a rotational system to offset rising production costs and improve

production field soil quality.

iii

Acknowledgements

I would first like to thank my advisor Dr. Erik Ervin and committee members Dr. Greg

Evanylo and Dr. Mike Goatley for their guidance, advice and patience during my research. I

would not have been able to do the research and achieve learning without their help and support.

Their recommendations and instructions have enabled me to assemble and finish the thesis

effectively. I would also like to thank my committee members for setting exemplary examples of

professionals. Whether it was public speaking, organizational skills or how to balance work and

life, my committee members were always open to questions throughout my educational career.

I would also like to thank all of the faculty and staff from Crop and Soil Environmental

Sciences who throughout my educational career have supported and encouraged me to believe in

my abilities. I am thankful to Frederick ‘Dickie’ Shepherd for all of the time and knowledge that

he shared with me and for teaching me to be resourceful, because sometimes the right tool for the

job is not the one you have. I am thankful to Dr. Xunzhong Zhang for his statistical advice, data

collection and analysis training and for being good friend. I owe a gratitude to Whitney Askew

and Michael Cox for their much needed advice on how to survive in the graduate studies. I can’t

express enough gratitude to Julia Burger, Steve Nagle and Dr. Jinling Li who assisted in setting

up laboratory equipment and procedures. Thanks to Justin Jones and Nate Reams for their help

collecting, processing and analyzing the hundreds of soil and plant samples. I am also thankful to

Scott Woodward and his staff at Woodward Turf Farms for providing the field operation support

for the research.

I am very thankful to my friends who endured and relieved all my complaints and

grievances along the course of this thesis. My graduate studies would not have been the same

iv

without their support. Finally, my deepest gratitude goes to my parents for their unfaltering love

and support throughout my life.

This research was financially supported by the United States Department of Agriculture

Specialty Crop Research Initiative (USDA SCRI).

v

Attributions

Chapter 3: Evaluation of a Biosolids-based Tall Fescue-Kentucky Bluegrass Sod

Production System in Virginia

Erik H. Ervin, PhD (Crop and Soil Environmental Sciences, Virginia Tech): Dr. Ervin was a co-

author for the manuscript and a principal investigator for the grant supporting the research.

Gregory K. Evanylo, PhD (Crop and Soil Environmental Sciences, Virginia Tech): Dr. Evanylo

was a co-author for the manuscript and a principal investigator for the grant supporting the

research.

Chapter 4: The Effects of Land Applying Biosolids for Sod Production on Soil Chemical

and Physical Properties and Soil Loss at Harvest

Gregory K. Evanylo, PhD (Crop and Soil Environmental Sciences, Virginia Tech): Dr. Evanylo

was a co-author for the manuscript and a principal investigator for the grant supporting the

research.

Erik H. Ervin, PhD (Crop and Soil Environmental Sciences, Virginia Tech): Dr. Ervin was a co-

author for the manuscript and a principal investigator for the grant supporting the research.

vi

Table of Contents

Abstract………………………………………………………………………………………..... ii

Acknowledgements…………………………………………………………………………….. iv

Attributions…………………………………………………………………………………….. vi

List of Tables……………………………………………...…………………………………..... ix

1. Introduction…………………………………………………………………………………... 1

1.1. Background………………………………………………………………………………….. 1

1.2. Objectives…………………………………………………………………………………… 4

1.3. References…………………………………………………………………………………… 6

2. Literature Review…………………………………………………………………………... 10

2.1. Biosolids Applications……………………………………………………………………... 10

2.2. Effects of Using Organic Soil Amendments on Soil and Turfgrass Quality………………. 11

2.4. References………………………………………………………………………………….. 16

3. Evaluation of a Biosolids-based Tall Fescue-Kentucky Bluegrass Sod Production System

in Virginia……………………………………………………………………………………… 21

3.1. Abstract…………………………………………………………………………………….. 22

3.2. Introduction………………………………………………………………………………… 24

3.3. Material and Methods……………………………………………………………………… 26

3.4. Results and Discussion…………………………………………………………………….. 31

3.5. Conclusions………………………………………………………………………………… 44

3.6. Acknowledgements………………………………………………………………………… 45

3.7. References………………………………………………………………………………...... 46

vii

4. The Effects of Land Applying Biosolids for Sod Production on Soil Chemical and

Physical Properties and Soil Loss at Harvest………………………………..………………. 57

4.1. Abstract…………………………………………………………………………………..… 58

4.2. Introduction……………………………………………………………………………….... 60

4.3. Material and Methods…………………………………………………………………….... 62

4.4. Results and Discussion…………………………………………………………………….. 66

4.5. Conclusions……………………………………………………………………………….... 71

4.6. Acknowledgements……………………………………………………………………….... 72

4.7. References………………………………………………………………………………….. 73

5. Conclusions………………………………………………………………………………..… 82

viii

List of Tables

Chapter 3: Evaluation of a Biosolids-based Tall Fescue-Kentucky Bluegrass Sod


Table 3.1. Average monthly temperature and precipitation for Remington, VA from August

2009 to August 2012. …………………………………………………………………………... 50

Table 3.2. Chemical and physical composition of the biosolids products. …………...……….. 50

Table 3.3. Target and Mean Actual Estimated First Year Plant Available Nitrogen (PAN)

Applied from Biosolids. …...…………………………………………………………………… 51

Table 3.4. Tall fescue-Kentucky bluegrass cover during the establishment season as influenced

by inorganic fertilizer and various levels of de-watered cake or blended biosolids in Remington,

VA from 2009-2012. …………………………………………………………………………… 52

Table 3.5. Nitrogen uptake of tall fescue-Kentucky bluegrass sod during the growing season in

Remington, VA from 2009-2012. ……………………………………………………..……….. 53

Table 3.6. Tall fescue-Kentucky bluegrass sod turfgrass quality during the growing season in

Remington, VA from 2009-2012. ……………………………………………..……………….. 54

Table 3.7. Tall fescue-Kentucky bluegrass clipping yields during the growing season in

Remington, VA from 2009-2012. ……………………………...………………………………. 55

Table 3.8. Tall Fescue-Kentucky bluegrass sod tensile strength at harvest in Remington, VA

from 2010-2012. …………………………………...…………………………………………... 56

Table 3.9. Tall fescue-Kentucky bluegrass sod transplant rooting strength four weeks after

transplant from 2010-2012. ………………………………………….…………………………. 56

ix

Chapter 4: The Effects of Land Applying Biosolids for Sod Production on Soil Chemical

and Physical Properties and Soil Loss at Harvest

Table 4.1. Chemical and physical composition of the biosolids products. …………...……….. 78

Table 4.2. Annual application rates of biosolids on a dry weight basis and N,P,K and C to

treatments in Remington, VA (2009-2011). …………………………………………………… 78

Table 4.3. Mehlich I soil extractable phosphorus of the surface soil to a 0-10 cm depth in

Remington, VA (2010-2012). ………………………………………………………………….. 79

Table 4.4. Soil organic matter and bulk density averaged over three production cycles (2009-

2012). …………………………………………………………………………………………... 80

Table 4.5. Mineral matter export at harvest each year (2010-2012). ………………………….. 81

x

1. Introduction

1.1. Background

As urban sprawl continues to expand into formerly rural land, disturbed soils created by

construction are typically stabilized with turfgrass. Turfgrass increases water infiltration as well

as reducing runoff and erosion (Beard, 1973). Although seeding is the least expensive turfgrass

establishment method, sodding is widely practiced in the United States. There were >1,800 sod

farms covering 165,000 hectares which generated $1.3 billion in total sales in 2007 (USDA,

2007). The demand for sod is expected to grow as metropolitan area population increases.

Population growth entails increasing wastewater treatment (Bastian, 1997) with resulting

sewage sludge waste by-product. Sewage sludge must either be disposed of or recycled into a

beneficial product. The United States Environmental Protection Agency (USEPA, 1993)

promulgated the Standards for the Use and Disposal of Sewage Sludge (Title 40, CFR, Part 503),

commonly referred to as The 503 Rule, in order to address disposal and beneficial use options.

In the 1990’s the wastewater treatment industry introduced “biosolids” as the term for treated

sewage sludge that can be used beneficially, most typically via land application as a soil

amendment and fertilizer source. The USEPA reported that 6.5 million dry Mg of biosolids were

produced in the U.S. as recently as 2004 (NEBRA, USDA, 2007).

The perishable nature of sod and the transportation costs to deliver sod to the install site

are the biggest limitations to sod production. These limitations cause sod to be produced near the

metropolitan areas they serve. Sod production has not typically benefited from biosolids

application, but sod farms could possibly benefit from using biosolids products as both nutrient

and organic matter replacement.

1

The amount of nitrogen that becomes available from land applying biosolids for crop

production is a concern. If mineralization of organic N is too low crop yields can be affected; if

mineralization is too high NO3- can accumulate in soil and potentially leach. Different biosolids

processing methods can influence nutrient availability (especially nitrogen and phosphorus)

(Maguire et al., 2001; Gilmour et al., 2003; Cogger et al., 2004).

Biosolids have been successfully employed to establish and maintain quality turfgrass in

previous studies (Landschoot and McNitt, 1994; Linde and Hepner, 2005; Loschinkohl and

Boehm, 2001; Schnell et al., 2009; Tesfamariam et al., 2009; Johnson et al., 2006; Norrie and

Gosselin, 1996). Researchers determined that incorporating biosolids enhanced establishment

and long-term turfgrass quality more than inorganic fertilizer alone (Linde and Hepner, 2005).

Loschinkohl and Boehm (2001) determined that biosolids acted like a slow release fertilizer; a

quicker greening response and greater turfgrass density was seen after turfgrass germination

using inorganic fertilizer, but biosolids amended soil maintained turfgrass with above acceptable

color and density longer than inorganic fertilizer. There have only been a few studies that have

used biosolids for sod production (Schnell et al., 2009; Tesfamariam et al., 2009). In these

studies the goal of the research was to produce acceptable quality sod, but utilize as much

biosolids as possible to export nutrients from production fields to install sites. The results of

these studies left gaps in the knowledge about the effects of lower rates of biosolids for sod

production, especially on cool-season grass species. Further research is needed to determine the

effects of N based biosolids rates for tall fescue-Kentucky bluegrass sod production on turfgrass

establishment, growth and quality.

There are only a few studies that have quantified the amount of soil export that occurs at

harvest during sod production (Sheard and Van Patter, 1978; Skogley and Hesseltine, 1978; Carr,

2

1996; Charbonneau, 2003; Millar et al., 2010). Results have been contradictory on whether or

not soil export is occurring. In a recent study on sod farms in Rhode Island that investigated soil

loss in sod production fields with varying years of production, it was found that significant soil

export of 74 to 114 Mg ha-1 occurred each year (Millar et al., 2010). Biosolids application could

reduce soil export at harvest. Tesfamariam et al. (2009) investigated the effects of excessive

biosolids application rates on sod production and found that rates above 8 dry Mg ha-1 reduced

soil export. Another study that applied and incorporated composted biosolids reported a

reduction in sod dry weight at harvest and concluded that less native soil was exported using

biosolids compared to treatments without (Schnell et al., 2009). Further research is needed to

investigate the effects of N based biosolids rates for sod production on the amount of mineral

matter export that occurs with sod harvest.

Soil quality is defined as "the ability of a specific kind of soil to function, within natural

or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance

water and air quality, and support human health and habitation" (Karlen et al., 1997). Soil quality

is assessed by measuring indicators, some of which are organic matter, bulk density and water

infiltration (Karlen et al., 1997). The application of biosolids has been shown to improve soil

quality by increasing organic matter and water retention and decreasing bulk density (Lindsay

and Logan, 1998; Epstein, 1975; Kelling et al., 1977; Kladivko and Nelson, 1979; Mays et al.,

1973; Aggelides et al., 2000). Research using biosolids in turfgrass settings has found similar

soil quality improvements (Johnson et al., 2006; Norrie and Gosselin, 1996). Although the

effects of biosolids on turf establishment and sod properties has been researched (Landschoot

and McNitt, 1994; Linde and Hepner, 2005; Loschinkohl and Boehm, 2001; Schnell et al., 2009;

Tesfamariam et al., 2009), there are no studies using biosolids that measured soil properties after

3

sod harvest. Further research is needed to investigate the effects of N based biosolids

applications on C cycling and organic matter accumulation.

Because of the unbalanced nature of biosolids in terms of plant nutrition, application of

biosolids at N based rates can result in the over application of phosphorus (Ott and Forster,

1978). Also, research has shown that repeated applications of biosolids increases soil phosphorus

(Chang et al., 1983; Kelling et al., 1977; Maguire et al., 2000). Previous research using biosolids

for sod production report that there is significant phosphorus and nitrogen export with each sod

harvest (Vietor et al., 2002; Schnell et al., 2009; Tesfamariam, et al., 2009). Schnell et al. (2009)

determined that more nutrients were exported when biosolids were topdressed compared to when

incorporated. The effects of biosolids application on soil phosphorus after sod harvest was only

reported once (Tesfamariam et al., 2009). The surface soil phosphorus was determined not to

increase with topdressed biosolids application rates less than 67 dry Mg ha-1. Further research is

needed to investigate the effects of incorporated N based biosolids application rates on P cycling

in sod production soil.

The evaluation of N based biosolids applications for sod establishment, quality, soil

export at harvest, soil quality and production field phosphorus accumulation is needed.

Additionally the mineralization rates of biosolids products with new processing methods need to

be evaluated in field settings.

1.2. Objectives

The overall goal of this research was to evaluate the effects of biosolids on tall fescue-Kentucky

bluegrass sod production. The specific objectives were to compare processing methods,

application and N mineralization rates of two biosolids products and an inorganic fertilizer

control for sod fertilization on: 1) agronomic parameters related to turfgrass quality, 2) the

4

amount of soil, C and P exported at harvest, and 3) chemical and physical properties of the soil

following sod harvest as an indicator of the benefits of biosolids use.

5

1.3. References

Aggelides, S.M., and P.A. Londra. 2000. Effects of compost produced from town wastes and

sewage sludge on the physical properties of a loamy and a clay soil. Bioresource

Technology. 71:253-259

Bastian, R. 1997. The biosolids (sludge) treatment, beneficial use, and disposal situation in

the USA. European Water Pollution Control Journal. 7:62-79.

Beard, J.B. 1973. Turfgrass: Science and culture. Prentice-Hall, Englewood Cliffs, NJ.

Carr, M.Y. 1996. Metal levels in Rhode Island municipal sewage sludges and their resulting

appropriateness for agricultural use by sod farms. Honors thesis. Brown Univ.,

Providence, RI.

Chang, A.C., A.L. Page, F.H. Sutherland, and E. Grgurevic. 1983. Fractionation of phosphorus

in sludge-affected soils. J. Environ. Qual. 12:286–290.

Charbonneau, P. 2003. Soil loss during sod production. Available at www.omafra.

gov.on.ca/english/crops/facts/info_sodprod.htm#loss (verified 1 Mar. 2013). Ontario

Ministry of Agriculture, Food and Rural Affairs, Ottawa.

Cogger, C.G., A.I. Bary, D.M. Sullivan, and E.A. Myhre. 2004. Biosolids processing effects on

first- and second-year available nitrogen. Soil Sci. Soc. Am. J. 68:162–167.

Epstein, E. 1975. Effect of sewage sludge on some soil physical properties. J. Environ. Qual.

4:139-142.

Evanylo, G. K. 1999. Agricultural land application of biosolids in Virginia: production

and characteristics of biosolids. Virginia Cooperative Extension. Pub. 452-304.

Gilmour, J.T., C.G. Cogger, L.W. Jacobs, G.K. Evanylo, and D.M. Sullivan. 2003.

6

Decomposition and plant-available nitrogen in biosolids: Laboratory studies, field

studies, and computer simulation. J. Environ. Qual. 32:1498–1507.

Johnson, G.A., J.G. Davis, Y.L. Quian, and K.C. Doesken. 2006. Topdressing turf with

composted manure improves soil quality and protects water quality. Soil Sci. Soc. Am. J.

70:2114–2121.

Karlen, D. L., M.J. Mausbach, J.W. Doran, R.G. Cline, R.F. Harris, and G.E. Schuman. 1997.

Soil quality: A concept, definition, and framework for evaluation. Soil Sci. Soc. Am. J.

61:4-10.

Kelling, K.A., A.E. Peterson, and L.M. Walsh. 1977. Effect of wastewater sludge on soil

moisture relationships and surface runoff. J. WPCF. 49:1698-1703.

Kelling, K.A., L.M. Walsh, D.R. Keeney, J.A. Ryan, and A.E. Peterson. 1977. A field study of

the agricultural use of sewage sludge: II. Effect on soil N and P. J. Environ. Qual. 6:345–

352.

Kladivko, E.J., and D.W. Nelson. 1979. Changes in soil properties from application of anaerobic

sludge. J. WPCF. 51:325-332.

Landschoot, P., and A. McNitt. 1994. Improving turf with compost. BioCycle. 35:54-57.

Linde , D.T., and L.D. Hepner. 2005. Turfgrass seed and sod establishment on soil amended with

biosolids compost. Horttechnology. 15:577-583.

Lindsay, B. J., and T.J. Logan. 1998 Field response of soil physical properties to sewage sludge.

J. Environ. Qual. 27:534–542.

Loschinkohl, C., and M.J. Boehm. 2001. Composted biosolids incorporation improves turfgrass

establishment on disturbed urban soils and reduces rust severity. Hort. Sci. 36(4):790-

794.

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Maguire, R.O., J.T. Sims, and F.J. Coale. 2000. Phosphorus solubility in biosolids-amended

soils in the Mid-Atlantic region of the USA. J. Environ. Qual. 29:1225–1233.

Maguire, R. O., J.T. Sims, S.K. Dentel, F.J. Coale, and J.T. Mah. 2001. Relationships

between biosolids treatment process and soil phosphorus availability. J. Environ.

Qual. 30:1023-1033.

Mays, D.A, G.L. Terman, and J.C. Duggan. 1973. Municipal compost: Effect on crop yield and

soil properties. J. Environ. Qual. 2:89-91.

Millar, D., M. Stolt, and J.A. Amador. 2010. Quantification and implications of soil losses from

commercial sod production. Soil Sci. Soc. Am. J. 74:892-897.

NEBRA (North East Biosolids and Residuals Association). 2007. A national biosolids

regulation, quality, end use and disposal survey-preliminary report. North East Biosolids

and Residuals Association. http://www.nebiosolids.org/uploads/pdf/NtlBiosolidsReport-

20July07.pdf.

Norrie, J., and A. Gosselin. 1996. Paper sludge amendments for turfgrass. Hort. Science. 31:957-

960.

Schnell, R.W., D.M. Vietor, R.H. White, T.L. Provin, and C.L. Munster. 2009 Effects of

composted biosolids and nitrogen on turfgrass establishment, sod properties, and nutrient

export at harvest. Hort. Sci. 44(6):1746-1750.

Sheard, R.W., and M. Van Patter. 1978. Soil modification during nursery sod production. Dep.

of Land Resource Science, Univ. of Guelph, Guelph, ON, Canada.

Skogley, C.R., and B.B. Hesseltine. 1978. Soil loss and organic matter return in sod production.

Univ. of Rhode Island, Kingston.

Tesfamariam, E.H., J.G. Annadale, and J.M. Steyn. 2009. Exporting large volumes of municipal

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sewage sludge through turfgrass sod production. J. Environ. Qual. 38:1320-1328.

USDA 2007. Census of Agriculture. USDA/AC/07/A-51. United States Department of

Agriculture, Washington D.C.

USEPA 1983. Process design manual for land application of municipal sludge.

USEPA-625/1-83-016. Washington, DC., U.S. Environmental Protection Agency.

USEPA 1998. Biosolids generation, use and disposal in the United States. US EPA/530/r-99/009.

United States Environmental Protection Agency Office of Solid Waste, Washington D.C.

USEPA 1993. 40 CFR part 503 Standards for the use and disposal of sewage sludge

subpart B Land Application. 503.10 to 503.18. Print., U. S. G. Washington, D.C.

Vietor, D.M., E.N. Griffith, R.H. White, T.L. Provin, J.P. Muir, and J.C. Read. 2002. Export

of manure phosphorus and nitrogen in turfgrass sod. J. Environ. Qual. 31:1731–1738.

9

2. Literature Review

2.1. Biosolids Applications

Land application of biosolids can supply crops with inexpensive plant essential nutrients.

Biosolids have been found to be more cost effective source of nutrients, especially nitrogen, than

inorganic fertilizers (Lagae et al., 2009; Lemainski and Silva, 2006; Faust and Oberst, 1996;

Chen et al., 2012). The majority of nitrogen in biosolids must be mineralized before it becomes

plant-available. Predicting the mineralization rates of organic-N in biosolids is the biggest

concern with land application. If the mineralization rates estimated from biosolids are not

accurate, either too little or too much N will be supplied to the crop. Such inaccuracies can result

in poor plant growth (too little) or N impairment of the environment (too much). Accurately

predicting the availability of nutrients in biosolids is difficult because it is dependent on the

biosolids processing method, climate and soil type (Maguire et al., 2001; Gilmour et al., 2003;

Cogger et al., 2004; Terry et al., 1979; Clark and Gilmour, 1983; Gilmour and Clark, 1988;

Sukkariyah et al., 2007).

One processing method is anaerobic digestion. Anaerobic digestion is a biological

treatment process that stabilizes biosolids (Evanylo, 1999). Organic matter decomposes into CO2

and methane resulting in lower amounts of pathogens, odor and organic matter. The USEPA

estimated that 20% of organic-N in anaerobically digested biosolids will be available the first

year of application (USEPA, 1983). The EPA also encouraged states to develop their own

mineralization estimates, suggesting that processing methods were a reliable indicator of

biosolids mineralization rates (USEPA, 1995). Further research on processing methods reported

that PAN in the first year of application did not correlate well to just processing method

10

(Gilmour and Skinner, 1999; Terry et al., 1979; Clark and Gilmour, 1983; Gilmour and Clark,

1988; Sukkariyah et al., 2007)

A study by Gilmour et al. (2003) used results from lab, field and computer modeling

studies to determine the mineralization rate of organic-N from an anaerobically digested

dewatered cake biosolids that was produced in Virginia (Alexandria Sanitation Authority,

Alexandria, VA). The results from this study provide the basis for the mineralization rates for

Virginia of 30 to 35%.

Biosolids generators are continually adopting new methods to process wastewater

residuals into beneficial products. Some of these new processing methods are aimed at

expanding the uses of biosolids by decreasing moisture content, ultimately making them easier to

handle. As these new products are developed research investigating the current mineralization

estimates with these new products is needed.

2.2. Effects of Using Organic Soil Amendments on Soil and Turfgrass Quality

Soil quality is defined as "the ability of a specific kind of soil to function, within natural

or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance

water and air quality, and support human health and habitation" and is assessed by measuring

indicators like organic matter, water retention and bulk density (Karlen et al., 1997). Previous

research has shown that using organic soil amendments, particularly biosolids, can improve soil

quality by increasing organic matter and water retention and decreasing bulk density (Lindsay

and Logan, 1998; Epstein, 1975; Kelling et al., 1977; Kladivko and Nelson, 1979; Mays et al.,

1973). Similar soil improvement results have been reported with organic amendments in

turfgrass settings as well. When paper sludge mixtures were used as amendment for turf

establishment, there was an increase in soil organic matter (Norrie and Gosselin, 1996). Johnson

11

et al. (2006) reported increased water retention and decreased bulk density when composted

biosolids were used to topdress turfgrass. Dunifon et al. (2011) amended severely disturbed

urban soils with compost applications and reported soil quality improvements that were related

to an increase in soil organic matter and overall availability of soil nutrients.

The turfgrass industry has traditionally used inorganic fertilizers to establish and maintain

quality turfgrass because of its relative ease of application and quick plant response. There have

been several studies that have compared the effectiveness of inorganic fertilizer to organic

fertilizer sources on turfgrass quality. Caceres et al., (2010), evaluated four cool season lawn

fertility programs that included three inorganic and one organic program and found no

significant differences in turfgrass quality and color between the programs. Carrow (1997)

showed that organic N sources fell short in producing immediate and intermediate high quality

turfgrass, but there were no differences over the long-term. Norrie and Gosselin (1996) evaluated

establishment of plots amended with paper mill sludge mixtures and determined that

supplemental nitrogen was needed to address the low nitrogen availability of the amendments.

Similar results were reported by Gardner (2004) and Trenholmn and Unruh (2005) evaluating the

nutrient value of composted tree mulch and vermicompost. They concluded that a reliable N

source rather than estimated N rate was needed to maintain high quality turfgrass.

Biosolids have also been used to establish and maintain turfgrass. Establishment and

growth of monocultures and mixed seedings of Kentucky bluegrass (Poa pratensis L. ‘Cheri’,

‘Baron’, and ‘Washington’) and perennial ryegrass (Lolium perenne L. ‘Accent’) were enhanced

by biosolids more than inorganic fertilizer alone, likely due to more plant available N and P

(Loschinkohl and Boehm, 2001). Landschoot and McNitt, (1994) reported similar establishment

using composted biosolids compared to inorganic fertilizer in nutrient deficient subsoils. Linde

12

and Hepner (2005) compared the effects of composted biosolids and inorganic fertilizer on

seeded Kentucky bluegrass (‘Touchdown’) establishment. Fall establishment was faster with

inorganic fertilizer, but there were no ground cover differences between the fertilizer and

biosolids treatments the following spring. Composted biosolids were also shown to increase

quality and growth of Kentucky bluegrass (‘Nuglade’) when topdressing applications were made

after core aeration. All of these studies used biosolids in urban settings, investigating

establishment and maintenance of turfgrass in its final destination, but establishment from seed is

not the only way to establish turfgrass in urban areas, sodding is also commonly used.

Sodding is a more expensive but commonly used establishment practice in the United

States. Several studies have evaluated biosolids applications for sod establishment. Schnell et al.

(2009) found that Tifway bermudagrass (Cynodon dactylon L. Pers. var. dactylon x C.

transvaalensis Burtt-Davey) coverage eight weeks after sprigging was 64% greater in soils with

incorporated than unincorporated composted biosolids. The increase in coverage was attributed

to greater sprig survival due to greater soil water retention and nitrogen availability.

Tesfamariam et al. (2009) reported good establishment of warm season grass with application

rates of heat-dried, anaerobically digested biosolids >8 dry Mg ha-1. The establishment success

was attributed to higher plant available nutrients with increasing rates of biosolids. Biosolids are

also commonly used as the fertilizer source for cool season sod produced in Rhode Island (Millar

et al., 2010). Application rates of 7 dry Mg ha-1 are typically used to achieve good turfgrass

establishment.

Soil phosphorus increases with repeated applications of biosolids to land, (Chang et al.,

1983; Kelling et al., 1977; Maguire et al., 2000). This is due to the high ratio of P to N in

biosolids and a resulting over application of P when supplying crop N needs (Ott and Forster,

13

1978). Soil P accumulation could be reduced with sod harvesting that removes considerable

amounts of P; thus, biosolids may be used more frequently in sod culture than other types of

turfgrass production.

Vietor et al. (2002) found that 77% of total P and 47% of N was exported at sod harvest

after topdressing organic amendments. Schnell et al. (2009) determined that topdressing

composted biosolids resulted in more nutrient export compared to when it was incorporated.

Tesfaramiam et al. (2009) reported that when anaerobically digested biosolids were applied at

-1, there was no accumulation of P in the top 15 cm of soil, concluding that there is

significant nutrient removal with each sod harvest. These studies investigated the effects of

biosolids on nutrient export and P accumulation using application rates higher than crop nutrient

needs. The excessive rates were used to provide sod with essential nutrients to successfully

establish once it is transplanted and to export nutrients from areas of high concentrations back to

urban areas that traditionally have nutrient deficient soils (Vietor et al., 2010, Richards et al.,

2008). There is still more information needed on what will happen to P accumulation when

biosolids are incorporated using lower application rates that match crop needs.

Soil export associated with sod harvest has been investigated in several studies,

estimating soil export to be in the range of 64-105 Mg ha-1 (Skogley and Hesseltine, 1978) and

74-114 Mg ha-1 (Millar et al., 2010) for sod harvest at a 1.25 cm depth. There are also several

studies that have found soil export to be insignificant, concluding that the residual root biomass

from the harvested sod that is left behind actually contributes up to 9 Mg ha-1 of soil back to

production fields (Sheard and Van Patter, 1978; Skogley and Hesseltine, 1978). Millar et al.

(2010) concluded that significant soil export is occurring with sod harvest based on results

indicating fields that had been in production the longest had shallower surface soil profiles.

14

Biosolids for sod production could reduce soil export. Schnell et al. (2009) reported lower dry

sod weight when using biosolids compared to inorganic fertilizer and concluded that the less

dense biosolids had diluted the surface soil enough to reduce native soil export. Tesfamariam et

al. (2009) reported that soil export was eliminated when 100 dry Mg ha-1 of biosolids were used

and lower rates reduced soil export proportionate to the biosolids application rate. Again these

studies used excessive rates of biosolids compared to plant nutritional needs. Biosolids were

incorporated in one (Schnell et al., 2009) but not the other (Tesfamariam et al., 2009) study.

Research on the effects of biosolids on soil export when lower rates are used and incorporated is

still needed.

Overall, research has shown that organic amendments and biosolids can establish and

maintain quality turfgrass. Also, the mineralization estimates of biosolids are dependent on many

factors including processing method, climate and soil type and Virginia has developed

mineralization estimates that work well for common biosolids sources in the state. Research has

also shown that land application of biosolids can improve soil quality in agricultural and

turfgrass settings. Biosolids can also be used for sod production and because of the soil export at

harvest significant nutrients are exported from production fields each year. There is still a need to

assess the nutrient availability of new biosolids products as they are developed to see if current

mineralization estimates will continue to work. Also, more information is needed on the effects

of incorporated applications of N based biosolids rates on soil quality improvements, soil P

accumulation and soil export during sod production.

15

2.4. References

Caceres, V.A., C.A. Bigelow, and D.S Richmond. 2010. Aesthetic and economic impacts

associated with four different cool-season lawn fertility and pesticide programs.

Horttechnology. 20:418-426.



Providence, RI.

Carrow, R.N. 1997. Turfgrass response to slow-release nitrogen fertilizers. Agron. J. 89:491-496.

Chang, A.C., A.L. Page, F.H. Sutherland, and E. Grgurevic. 1983. Fractionation of phosphorus in

sludge-affected soils. J. Environ. Qual. 12:286–290.




Chen, H., S.H. Yan, Z.L. Ye, H.J. Meng, and Y.G. Zhu. 2012. Utilization of urban sewage

sludge: Chinese perspectives. Environmental Science and Pollution Research. 19:1454-

1463.

Clark, M.D., and J.T. Gilmour. 1983. The effect of temperature on decomposition at optimum

and saturated soil water contents. Soil Sci. Soc. Am. J. 47:927–929.

Cogger, C.G., A.I. Bary, D.M. Sullivan, and E.A Myhre. 2004. Biosolids processing effects on

first- and second-year available nitrogen. Soil Sci. Soc. Am. J. 68:162–167.

Dunifon, S.N., G.K. Evanylo, R.O. Maguire, and J.M. Goatley, Jr. 2011. Soil nutrient and fescue

(Festuca spp.) responses to compost and hydroseed on a disturbed roadside. Compost

Science and Utilization. 19:147-151.

16

Epstein, E. 1975. Effect of sewage sludge on some soil physical properties. J. Environ. Qual.

4:139-142.

Evanylo, G. K. 1999. Agricultural land application of biosolids in Virginia: production

and characteristics of biosolids. Virginia Cooperative Extension. Pub. 452-304.

Faust, T.G., and R.L Oberst. 1996. Economic value of biosolids to farmers. Biocycle. 37:67-69.

Gardner, D.S. 2004. Use of vermicomposted waste materials as a turfgrass fertilizer. Hort.

Technology. 14:372-375.

Gilmour, J.T., and M.D. Clark. 1988. Nitrogen release from wastewater sludge: A site-specific

approach. J. Water Pollut. Control Fed. 60:494–498.

Gilmour, J.T., C.G. Cogger, L.W. Jacobs, G.K., Evanylo, and D.M. Sullivan. 2003.



Johnson, G.A., Y.L. Qian, and J.G. Davis. 2009. Topdressing Kentucky bluegrass with compost

increases soil water content and improves turf quality during drought. Compost Science

and Utilization. 17:95-102.

Karlen, D. L., M.J. Mausbach, J.W. Doran, R.G. Cline, R.F. Harris, and G.E. Schuman. 1997.

Soil quality: A concept, definition, and framework for evaluation. Soil Sci. Soc. Am. J.

61:4-10.

Kelling, K.A., A.E. Peterson, and L.M. Walsh. 1977. Effect of wastewater sludge on soil

moisture relationships and surface runoff. J. WPCF. 49:1698-1703.



352.

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Kladivko, E.J., and D.W. Nelson. 1979. Changes in soil properties from application of anaerobic

sludge. J. WPCF. 51:325-332.

Lagae, H.J., M. Langemeier, D. Lybecker, and K. Barbarick. 2009. Economic value of biosolids

in a semiarid agroecosystem. Agron. J. 101:933-939.




Lindsay, B. J., and T.J. Logan. 1998 Field response of soil physical properties to sewage sludge.

J. Environ. Qual. 27:534–542.

Lemainski, J., and J.E. da Silva. 2006. Agronomic and economic evaluation of biosolids

application on soybean production. Pesquisa Agropeauaria Brasileira. 41:1477-1484.



794.

Maguire, R.O., J.T. Sims, and F.J. Coale. 2000. Phosphorus solubility in biosolids-amended soils

in the Mid-Atlantic region of the USA. J. Environ. Qual. 29:1225–1233.

Maguire, R. O., J.T. Sims, S.K. Dentel, F.J. Coale, and J.T. Mah. 2001. Relationships

between biosolids treatment process and soil phosphorus availability. J. Environ.

Qual. 30: 1023-1033.

Mays, D.A, G.L. Terman, and J.C. Duggan. 1973. Municipal compost: Effect on crop yield and

soil properties. J. Environ. Qual. 2:89-91

Millar, D., M. Stolt, and J.A. Amador. 2010. Quantification and implications of soil losses from


18


960.

Richards, C.E., C.L. Munster, D.M. Vietor, J.G. Arnold, and R. White. 2008. Assessment of a

turfgrass sod best management practice on water quality in a suburban watershed. J.

Environ. Management. 86:229-245.

Schnell, R.W., D.M. Vietor R.H. White, T.L. Provin, and C.L. Munster. 2009 Effects of





Sukkariyah, B., G. Evanylo, and L. Zelazny. 2007. Distribution of copper, zinc, and

phosphorus in coastal plain soils receiving repeated liquid biosolids applications.

J. Environ. Qual. 36: 1618-1626.

Terry, R.E., D.W Nelson, and L.E. Sommers. 1979. Decomposition of anaerobically digested

sewage sludge as affected by soil environmental conditions. J. Environ. Qual. 8:342–347.



Trenholm, L. E., and J.B. Unruh. 2005. Warm-season turfgrass response to fertilizer rates and

sources. J. Plant Nutrition. 28:991-999.

USEPA 1983. Process design manual for land application of municipal sludge.

USEPA-625/1-83-016. Washington, DC., U.S. Environmental Protection Agency.

USEPA 1995. Process design manual: Land application of sewage sludge and domestic

septage. USEPA Rep. 625/R-95/001. USEPA. Washington, D.C., U.S. Gov. Print.

19

Office.



Vietor, D.M., R.W. Schnell, C.L. Munster, T.L. Provin, and R.H. White. 2010. Biosolid and

alum effects on runoff losses during turfgrass establishment. Bioresource Technology.

101:3246-3252.

20

3. Evaluation of a Biosolids-based Tall Fescue-Kentucky Bluegrass Sod


J. Derik Cataldi*, Erik H. Ervin, and Gregory K. Evanylo

Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and

State University, Blacksburg, VA 24061

*Corresponding author ([email protected])

21

3.1. Abstract

Biosolids can be used to establish and maintain quality turfgrass, but the effectiveness of

a N-based biosolids sod production system warrants further investigation. The objective of this

study was to compare processing methods and application rates of anaerobically digested

biosolids and an inorganic fertilizer control on agronomic parameters related to turfgrass sod

production. The study was conducted on a sod farm in Remington, Virginia on a silt loam

Ashburn-Dulles complex from 2009 to 2012. The biosolids products were applied at estimated

plant available nitrogen (PAN) rates of 98 kg ha-1 (0.5X), 196 kg ha-1 (1.0X), 294 kg ha-1 (1.5X)

for a tall fescue (Festuca arundinacea Schreb. ‘Rebel Exeda’, ‘Rebel IV’ and ‘Justice’)/

Kentucky bluegrass (Poa pratensis L. ‘Midnight’) mixture (85/15 % by weight) and plots were

seeded at 236 kg ha-1. One biosolids product was a dewatered cake applied at 15, 30.5 and 46

wet Mg ha-1. The second biosolids product was the same dewatered cake blended with wood

fines applied at 17, 34 and 51 wet Mg ha-1. The biosolids treatments were compared to an

inorganic fertilizer control that supplied 196 kg N ha-1 through three applications over the

production cycle. There were no differences in establishment between the cake biosolids

treatments and the inorganic fertilizer control, but all of the blended biosolids were slower to

establish. Only the 1.0X and 1.5X PAN rates from the cake biosolids matched the inorganic

fertilizer control in producing an acceptable quality sod in ten months. Lower nitrogen uptake

between the blended biosolids treatments compared to the inorganic fertilizer control and lower

although acceptable sod quality ratings at harvest of the 1.0X cake biosolids indicate our PAN

estimates of 30% organic nitrogen mineralization overestimated the PAN for both materials.

There were no differences in biomass yields between the 1.5X cake biosolids treatment and the

inorganic fertilizer control. The rest of the biosolids treatments yielded less biomass than the

22

fertilizer control. There were no differences in sod tensile strength between the 1.5X cake

biosolids and inorganic fertilizer control, but the other biosolids treatments gave lower tensile

strength. There were no differences in transplant rooting strength among all treatments. A one-

time application of anaerobically digested dewatered biosolids cake at the 1.5X rate was able to

produce sod comparable to inorganic fertilizer. Supplemental nitrogen may be needed to improve

the performance of the 1.0X cake biosolids rate, which is also the upper limit of biosolids

application for sod production in Virginia.

23

3.2. Introduction

In recent years the cost of sod production has increased because of the rising prices of

inorganic fertilizer and fuel (NASS, USDA, 2011). At the same time, wastewater treatment

facilities have been dealing with the rising costs of sewage sludge disposal. Because organic

sources of nutrients, including biosolids, can be used to successfully establish turfgrass (Dunifon

et al., 2011, O’Brien and Barker, 1996; Richards et al., 2008; Wright, 2007), the beneficial use of

these organic residuals could alleviate wastewater sludge disposal limitations while providing

inexpensive alternative nutrient sources for sod growers.

Due to fewer land application restrictions and ease of handling, composted biosolids have

been the predominant type of biosolids used in urban turfgrass settings. A comparison between

the effects of composted biosolids and inorganic fertilizer on seeded Kentucky bluegrass (Poa

pratensis L. ‘Touchdown’) establishment was studied by Linde and Hepner (2005). Fall

establishment was faster with inorganic fertilizer, but there were no ground cover differences

between the fertilizer and biosolids treatments the following spring. They concluded that

biosolids provided long-term supply of nutrients. Establishment and growth of monoculture and

mixed seedings of Kentucky bluegrass (‘Cheri’, ‘Baron’, and ‘Washington’) and perennial

ryegrass (Lolium perenne L. ‘Accent’) were enhanced by biosolids more than inorganic fertilizer

alone, likely due to more plant available N and P (Loschinkohl and Boehm, 2001). Schnell et al.

(2009) found that bermudagrass (Cynodon dactylon L. Pers. var. dactylon x C. transvaalensis

Burtt-Davey) coverage eight weeks after sprigging was 64% greater in soils that had

incorporated composted biosolids than those without. The increase in coverage was attributed to

greater sprig survival due to increased soil water retention and nitrogen availability.

24

Although biosolids use has been shown to successfully establish turfgrass, there has been

little research on biosolids for sod production (Schnell et al., 2009; Tesfamariam et al., 2009).

Sod is produced in rural areas, lending itself for the use of non-composted biosolids. The use of

non-composted biosolids for sod production was studied by Tesfamariam et al. (2009). They

found that when heat-dried anaerobically digested biosolids were applied at rates estimated to

exceed turfgrass nutrient needs, there were no detrimental effects on growth or establishment.

Rates above the South African upper limit of 8 dry Mg ha-1 enhanced turfgrass establishment.

The use of biosolids for sod production also improves sod properties by increasing turfgrass

quality and tensile strength at harvest (Schnell et al., 2009; Tesfamariam et al., 2009).

The application rates commonly recommended for sod production in Virginia are based

on biosolids mineralization estimates for composted and anaerobically digested and dewatered

biosolids (Virginia Department of Conservation and Recreation, 2005), but PAN is often

unknown for alternative biosolids products that are constantly being developed for urban use.

Such Exceptional Quality (EQ) products, (USEPA, 1993), can be used in public access settings

due to their low pollutant concentrations and pathogen-free status.

The PAN of the anaerobically digested, dewatered cake biosolids from the Alexandria

Sanitation Authority (Alexandria, VA) has been tested in previous lab and field studies (Gilmour

et al., 2003). Based on those results the biosolids mineralization estimates for the state of

Virginia are 30-35%. Although the Alexandria biosolids are de-watered, they have moisture

contents ~700 g kg-1. To further reduce this water content, enabling ease of handling in urban

areas, and expanding the use of this EQ biosolids product, wood fines were blended with the

cake. This lowered the moisture content to around 300 g kg-1 and increased the C:N ratio to

25

~15:1, which was expected to reduce nitrogen availability. Both the de-watered cake and blended

product will be evaluated in our study.

Nitrogen availability and turfgrass-enhancing value of such newly developed EQ

biosolids products warrant research because such uses are novel. Commonly used composts

differ from non-composted products in N availability (Eghball, 2000; Flavel and Murphy, 2006),

and few studies have evaluated EQ non-composted biosolids for turf production. The objective

of this study was to compare processing method and application rates of two biosolids products

and an inorganic fertilizer control on agronomic parameters related to turfgrass quality in sod

production.

3.3. Materials and Methods

Site, experimental design, and treatment establishment

The study was conducted on a sod farm in Remington, VA (Lat. +38.51417, Long. -

77.811717) on a silt-loam Ashburn-Dulles complex (Fine-silty, mixed, active, mesic Oxyaquic

Hapludalfs). The study was conducted from the fall of 2009 until the summer of 2012. Mean

monthly temperature and precipitation for the duration of the study were obtained from nearby

weather stations (NOAA, 2013).

The study consisted of seven treatments, each replicated 4X and arranged in a

randomized complete block design. The treatments included three rates (0.5X, 1.0X and 1.5X

agronomic N rate) of each of two types of biosolids and a fertilizer control, according to Virginia

Tech Soil Testing Laboratory recommendations (Donohue and Heckendorn, 1994). The 0.5X,

1.0X, and 1.5X treatments were designed to apply 98 kg ha-1, 196 kg ha-1, and 294 kg ha-1 of

plant available nitrogen (PAN), respectively. Plot dimensions were 61 m by 11 m, which

necessitated biosolids applications made using a commercial side-discharge manure spreader.

26

An EQ anaerobically digested, dewatered biosolids cake (Alexandria Sanitation

Authority, Alexandria, VA) and the same material blended with wood fines (blended by

Synagro, Inc., Champlain, VA) at a 1:0.65 by weight ratio of biosolids to wood fines were used.

Biosolids were applied in the fall (Aug. 26, 2009, Sept. 8, 2010, and Oct. 12, 2011) of each year

based on their estimated supply of plant available nitrogen assuming 30% of the organic nitrogen

is mineralized in the first year (Virginia Department of Conservation and Recreation, 2005).

Although the organic nitrogen content and application rate of the biosolids varied slightly from

year to year the three-year mean biosolids rates were 15, 30.5 and 46 wet Mg ha-1 of cake

biosolids, respectively, and 17, 34 and 51 wet Mg ha-1 of blended biosolids, respectively. The

inorganic fertilizer control treatment supplied 196 kg N ha-1, whose application was split to

provide 74 kg N ha-1 (as urea and diammonium phosphate, DAP) at seeding, 74 kg N ha-1 (as

calcium ammonium nitrate) in mid-October, and 48 kg N ha-1 (as calcium ammonium nitrate) in

late-April. The DAP rate was calculated to meet the soil test recommended amount of

phosphorus and incorporated to a depth of five cm.

Samples from each biosolids source were collected at application dates and sent to A&L

Eastern Laboratories in Richmond, VA and analyzed for total solids (SM-2540G), total Kjeldahl

N (SM-4500- TKN), ammonium-N (SM-4500-NH3) (Standard Methods for the Examination of

Water and Wastewater, 1992), phosphorus (SW-846-6010C), potassium (SW-846-6010C) (U.S.

Environmental Protection Agency, 1986), and other macro and micro nutrients. The cake

biosolids was composed of 339 g kg-1 C, 5l.1 g kg-1 TKN, 35.6 g kg-1 P, 1.5 g kg-1 K and had a

moisture content around 700 g kg-1. The blended biosolids were composed of 230 g kg-1 C, 15.0

g kg-1 TKN, 9.7 g kg-1 P, 2.6 g kg-1 K and had a moisture content ~300 g kg-1. The 0.5X, 1.0X

and 1.5X cake biosolids rates applied 117, 235 and 352 kg of estimated PAN ha-1 respectively;

27

154, 308 and 462 kg P ha-1 respectively; and 1,525, 3,051, and 4,576 kg C ha-1 respectively. The

0.5X, 1.0X and 1.5X blended biosolids rates applied 90, 180 and 270 kg of estimated PAN ha-1

respectively; 105, 210 and 315 kg P ha-1 respectively; and 2,530, 5,060, and 7,820 kg C ha-1

respectively.

All plots were seeded with a Brillion Turfmaker (Brillion Farm Equipment, Brillion, WI)

at 236 kg ha-1 with an 85% tall fescue (Festuca arundinacea Schreb. ‘Rebel Exeda’ ‘Rebel IV’

and ‘Justice’)/ 15% Kentucky bluegrass (Poa pratensis L. ‘Midnight’) mixture, by weight. Plots

were seeded Sept. 2 in 2009; Sept. 14 in 2010; Oct. 12 in 2011. Plots were maintained at a 7.6

cm height throughout the growing season and clippings were returned.

Sampling and analysis

In the fall of 2009 soil cores with a 1.9 cm diameter were randomly collected from the 0-

10 cm depth at the study site, air-dried, ground to pass through a 2 mm sieve and sent to Virginia

Tech Soil Testing Laboratory for routine soil test analysis of Mehlich 1 extractable P, K, and pH

and Walkley-Black soil organic matter content (Maguire and Heckendorn, 2011). Results

indicated a pH of 6.1, extractable P and K of 12 mg kg-1 and 43 mg kg-1 respectively and soil

organic matter content of 32 mg kg-1. Fertilizer P recommendations for the inorganic fertilizer

control plots and K recommendations for all treatments were made using soil testing results

(Virginia Department of Conservation and Recreation, 2005). Establishment was tracked using

digital image analysis (DIA) from three sample locations per plot every two weeks from seed

germination to >95% cover. Sampling dates were Oct. 27, Nov. 10, Nov. 24 and Dec. 1 in 2009;

Oct. 12, Oct. 26 and Nov. 8 in 2010; Nov. 17 in 2011 and Mar. 15, Apr. 12 and May 24 in 2012.

The images were taken with a Canon Powershot 3.1 mega pixel digital camera (Melville, NY)

and analyzed using SigmaScan® software (Systat Software Inc., San Jose, CA) with a macro

28

developed specifically to analyze percent turfgrass cover (Richardson et al., 2001). The digital

pictures were taken in a controlled environment created by using a light-box that simulates

daylight wavelengths at high noon (standard method for DIA).

Turfgrass quality of the entire plot was visually rated every two weeks after >95% cover

was reached. Rating dates were Mar. 23, Apr. 20, May 18 and Jun. 15 in 2010; Apr. 8, May 6,

Jun. 3, and Jul. 1 in 2011; May 25, Jun. 22, Jul. 20 and Aug. 17 in 2012. Quality was rated on a

1-9 index scale with 1 being poorest turfgrass quality and 9 being perfect turfgrass; a

commercially acceptable value was set at 6 (Morris, 2004).

Broadleaf weed pressure measurements were made Apr. 20 in 2010, Apr. 8 in 2011 and

Apr. 13 in 2012 using the line intersect method (Laycock and Canaway, 1980). A 1.2 m2 quadrat

was randomly placed in five locations within each plot. The number of intersects where weed

species were found was divided by the total number of intersects in the quadrant for a percentage

of broadleaf weeds. One day after measurements, the broadleaf weeds were treated with 1.1 kg

2,4-D (2,4-dichlorophenoxyacetic acid) ha-1.

Disease ratings were made Apr. 20, May 18 and Jun. 15 in 2010; May 6, Jun. 3, and Jul.

1 in 2011; May 25, Jun. 22, Jul. 20 and Aug. 17 in 2012. Disease damage was rated on a 1-9

scale with 1 being 100% damaged turf and 9 being no injury (Morris, 2004).

Turfgrass clippings for biomass yield were collected monthly when the slowest growing

plot reached a height of 10 cm. Clipping yields for a seven day period were determined on a 1.8

m by 0.45 m area in each plot with a HRX217VKA Honda (America Honda Power Equipment

Division, Alpharetta, GA) gasoline powered walk-behind rotary mower. The clippings were

dried to a constant weight at 55°C, cleaned of any non-clipping debris and weighed. Sampling

29

dates were May 18 and Jun. 15 in 2010; May 6, Jun. 3, and Jul. 1 in 2011; Jun. 22, Jul. 20 and

Aug. 17 in 2012.

Sub-samples from each clipping sample date were analyzed for carbon and nitrogen by

gas analysis using high heat combustion at 1200°C in a Vario Max CNS macro elementar

analyzer (Elementar, GER). Nitrogen uptake for each sampling date was determined by

multiplying N concentration (g N kg-1) in the turfgrass tissue by the dry mass clipping yield (kg

ha-1) for each treatment.

Sod was harvested 10 months, or 40 weeks, after seeding using a Trebro Autostack

automatic harvester (Trebro Mfg. Inc., Billings, MT) and transported to the Turfgrass Research

Center at Virginia Tech for processing. Sod harvest depth in year one was 2.54 cm; harvest depth

was 1.9 cm in years two and three. The tensile strength of three pieces of sod, 91 cm by 61 cm,

randomly harvested from each plot, was measured using a sod stretcher (Goatley and Schmidt,

1991).

Transplant rooting strength was measured on three pieces of sod, 30.5 cm by 30.5 cm.

Pieces were randomly selected from each plot and placed on rooting frames situated on bare

mineral soil (Groseclose silt loam) to simulate new establishment (Schmidt et al., 1986). The

sod pieces were hand-watered with 0.64 cm of water daily for one week and then as needed for

three weeks. After a four week establishment period, hooks were attached to the corners of the

rooting frames and the force required to free the pieces of sod from the ground was measured

using a Chatillon hand held force gauge (Chatillon, Largo, FL).

Establishment, nitrogen uptake, turfgrass quality, clipping yields, sod tensile strength and

transplant rooting strength data were subjected to analysis of variance using SAS Proc GLM

(SAS Institute, 2008) to test the effects of treatments on agronomic parameters related to sod

30

production. Means were separated using a Protected LSD at P There were significant

year by treatment interactions for all parameters measured. Each year of turfgrass establishment,

nitrogen uptake, quality, clipping yield, sod tensile strength and transplant rooting strength date

are presented separately.

3.4. Results and Discussion

3.4.1 Temperature and precipitation

Average temperature and precipitation per month at the site is shown in Table 3.1. The 30

year average temperature for the site was 12.9 °C and the 30 year average rainfall was 105.5 cm.

Average rainfall for each production cycle was 86.6 cm with a range of +/- 2.9. Weather

conditions delayed seed germination in 2009. Plots were seeded the first week of September, but

the study site did not receive adequate rainfall to promote germination until the end of the month.

Weather conditions also delayed seeding in 2011. Plots were not seeded until mid-October

because of rainfall on scheduled biosolids application dates postponed application. The delayed

seeding in 2011 altered the inorganic fertilization schedule.

3.4.2. Biosolids composition and application

The properties of the two biosolids are shown in Table 3.2. The cake biosolids had more

than three times the amount of TKN, NH4+-N, organic-N and total P than the blended biosolids.

Although the amounts of N and P were three times greater in the cake biosolids, the ratio of N:P

was similar for both products (1.5:1). The target and mean estimated actual PAN applied each

year of the study are shown in Table 3.3, along with the applied total P and K. The target N rates

were not exactly achieved with the two biosolids products. The application method was difficult

to calibrate for the low amounts of product being applied at the 0.5X agronomic N rates and

31

resulted in slightly over applying the estimated N in the cake biosolids treatments and slightly

under applying the estimated N in the blended biosolids treatments.

3.4.3. Turfgrass establishment

In year one, germination was delayed because of lack of moisture (Table 3.4) despite the

early season planting date. There were no differences in vegetative cover among the biosolids

treatments and the inorganic fertilizer control until 11 weeks after seeding (WAS). From 11

through 13 WAS, there was less vegetative cover in the 0.5X cake, 0.5X and 1.0X blended

biosolids treatments than in the inorganic fertilizer control. These dates correspond to the middle

and end of November respectively.

In year two plots were seeded in the middle of September. Timely rainfall enabled the

mid-September-seeded plots to establish rapidly. At four WAS, the 0.5X and 1.0X cake and

blended biosolids treatments had lower vegetative cover compared to the inorganic fertilizer

control, but those differences declined as establishment continued. The only treatment at 8 WAS

that had lower vegetative cover than the inorganic fertilizer control was the 0.5X blended

biosolids treatment.

Year three seeding (mid-October) was delayed because there was standing water on the

study site the day biosolids were scheduled to be applied. This, combined with biosolids

availability issues afterwards, further delayed application. In the two previous years all of the

plots had reached greater than 75% vegetative cover by the end of November, after which no

further establishment measurements were done. Because of the late seeding in year three, only

one establishment measurement was performed in the fall, and additional measurements were

made the following spring. At five WAS, there were no differences among treatments (Table

3.4). At 22 WAS, there were no differences among the 0.5X and 1.0X cake biosolids treatments

32

and inorganic fertilizer control. At this time, there was lower vegetative cover for all of the

blended biosolids treatments, and higher vegetative cover for the 1.5x cake biosolids treatment

compared to the inorganic fertilizer control. After the second application of inorganic fertilizer

(22 WAS), there were no differences in vegetative cover between the cake biosolids treatments

and the inorganic fertilizer control. However, there was less vegetative cover in the blended

biosolids treatments than in the inorganic fertilizer control. Adequate turfgrass coverage during

the establishment period was limited by the late seeding date the most in the blended biosolids

treatments.

The data indicate that lower application rates of the blended biosolids resulted in

turfgrass establishment at a slower rate than the inorganic fertilizer control; however, there were

no differences in establishment rates between the cake biosolids treatments and inorganic

fertilizer. These results support the conclusion that we better estimated the PAN from the

anaerobically digested, dewatered cake than from the blended biosolids, if the limitation in

establishment was due to inadequate nitrogen.

There has been very little research on turfgrass establishment using non-composted

biosolids. Linde and Hepner (2005) found that a one-time fertilizer application treatment at

seeding resulted in a better establishment rate than composted biosolids alone. When composted

biosolids treatments with a starter fertilizer were compared to treatments with just inorganic

fertilizer, enhanced turfgrass establishment occurred with the composted biosolids treatments

(Loschinkohl and Boehm, 2001, Schnell et al., 2009). The starter fertilizer was used to overcome

the slowly available nitrogen in the composted organic materials (Flavel and Murphy, 2006).

These results suggest that there is a PAN and turfgrass N need synchrony issue with composted

33

biosolids and they are not as effective for turfgrass establishment when applied at a similar

estimated PAN rate as inorganic fertilizer unless a starter fertilizer is used.

The results of our study are similar to Tesfamariam et al. (2009), who used oven-dried

anaerobically-digested biosolids at varying application rates, at and above estimated turfgrass

nutritional needs, and reported good turfgrass establishment with rates as low as 8 dry Mg ha-1.

Although application rates and biosolids moisture varied slightly, on average each year in our

study we applied 4.5, 9 and 13.5 dry Mg ha-1 of cake biosolids and 11, 22 and 34 dry Mg ha-1 of

blended biosolids with our 0.5X, 1.0X and 1.5X rates respectively. Tesfamariam et al. (2009)

also reported an increased rate of establishment with higher biosolids rates and suggested that

production time could be decreased when using higher application rates. Higher than plant

estimated nutrient need biosolids rates were also tested in our study, but we did not see similar

results, most likely because our highest rates were more than 65 dry Mg ha-1 less than the highest

rate used in Tesfamariam et al. (2009). Our results support previous literature (Loschinkohl and

Boehm, 2001; Schnell et al., 2009; Linde and Hepner, 2005; Tesfamariam et al., 2009) reporting

that commercially acceptable turfgrass establishment is dependent on the biosolids source,

particularly on how it has been processed after treatment.

3.4.4. Nitrogen uptake

Nitrogen uptake as kg N ha-1 was measured from turfgrass clipping yields collected in the

spring of each year (Table 3.5). In year one, the inorganic fertilizer control N uptake was higher

than all of the biosolids treatments at 36 WAS. By 40 WAS, there was no difference in N uptake

between the 1.5X cake biosolids and the inorganic fertilizer control. All other biosolids

treatments resulted in lower N uptake.

34

In year two, there were no differences among the 1.0X, 1.5X biosolids treatments and the

inorganic fertilizer control across all sampling dates (32, 36 and 40 WAS). All other biosolids

treatments had lower N uptake (Table 3.5).

In year three, the 1.5X biosolids treatment had higher nitrogen uptake than the inorganic

control at 32 WAS. There were no differences in uptake among the other biosolids treatments

and the inorganic fertilizer control. At 36 WAS, the 1.0X and 1.5X cake biosolids treatments

had higher nitrogen uptake than the inorganic fertilizer control, and there were no uptake

differences among the inorganic fertilizer control and the rest of the biosolids treatments. By 40

WAS, nitrogen uptake by the 1.5X cake biosolids treatment was higher than the inorganic

fertilizer control, and there were no differences among the rest of the biosolids treatments and

inorganic fertilizer control.

The nitrogen uptake results indicate that the low rates of cake and blended biosolids had

lower nitrogen availability than the inorganic fertilizer control. This was expected since the low

rates of biosolids were only estimated to supply about half of the PAN as the inorganic fertilizer

control. The lower nitrogen uptake from the 1.0X and 1.5X blended biosolids than the inorganic

fertilizer control was unexpected. We suspect that the estimated PAN in the blended biosolids

product was lower due to greater N immobilization by the high carbon-containing, fine particle-

sized, wood fines that were blended with the dewatered cake. The nitrogen uptake of the 1.0x

and 1.5X cake biosolids was similar to the inorganic fertilizer control, indicating that these

biosolids mineralized similar PAN as the inorganic fertilizer control and support our 30%

mineralization PAN estimate for the anaerobically digested, dewatered cake biosolids. Also, our

results show that, as temperature increased and with adequate rainfall (Table 3.1), there was a

noticeable increase in turfgrass quality among all of the biosolids treatments. This increase was

35

also shown with the inorganic fertilizer control and correlates to the spring application of

fertilizer. This trend and the ability of the 1.0X and 1.5X cake biosolids rates to produce

acceptable quality sod indicate that the N availability of the cake biosolids in Remington, VA

matches the growth pattern of tall fescue-Kentucky bluegrass sod.

3.4.5 Turfgrass quality

The first turfgrass quality rating in year one was not taken until mid-March (28 WAS)

because of the slow growth and suspected slower mineralization rates during the winter months

(Table 3.6). The only treatment that had lower turfgrass quality than the inorganic fertilizer

control was the 0.5X blended biosolids treatment. At 32 WAS and through sod harvest all of the

biosolids treatments except the 1.5X cake biosolids treatment had lower turfgrass quality than the

inorganic fertilizer control. And only the 1.0X and 1.5X cake biosolids treatments and inorganic

fertilizer control had acceptable quality at harvest. These results, supported by the differences in

our nitrogen uptake results, indicate that the amount of PAN that had mineralized from the

blended biosolids and low cake biosolids treatments was not enough to produce an acceptable

quality sod. We expected the quality ratings of the 1.0X and 1.5X biosolids treatments from each

biosolids source to be similar to the inorganic fertilizer control because we calculated 1.0X

biosolids rates to provide a similar amount of PAN as the inorganic fertilizer. The lower quality

ratings with the blended biosolids treatments may not have occurred because of inadequate total

PAN, but instead caused by poor synchrony between the spring and early summer tall fescue-

Kentucky bluegrass N needs and PAN.

In year two, all biosolids treatments, except 1.5X cake, had lower quality ratings than the

inorganic fertilizer at 28 WAS (early April) (Table 3.6). Following the final inorganic fertilizer

application at 30 WAS, all of the blended biosolids and the 0.5X and 1.0X cake biosolids had

36

lower quality ratings than the inorganic fertilizer control at 32 WAS and 36 WAS. Only the

1.0X and 1.5X cake biosolids treatments and the inorganic fertilizer control had acceptable

turfgrass quality at harvest, and there were no differences in quality ratings among treatments.

The results from year two continue to support the conclusions that there is a PAN and turfgrass

N need synchrony issue with the blended biosolids and that the 0.5X biosolids treatments did not

provided enough N to produce an acceptable quality sod.

In year three, a quality rating at 28 WAS (mid-May) was made due to delays in seeding

and the inorganic fertilization. At 28 and 32 WAS, all biosolids treatments except the 1.5X cake

had lower quality ratings than the inorganic fertilizer control (Table 3.6). After the second

application of inorganic fertilizer (28 WAS), only the blended biosolids treatments had lower

turfgrass quality ratings than the inorganic fertilizer control at 36 WAS. The quality ratings of

the 0.5X and 1.0X cake biosolids treatments were not different than the inorganic fertilizer

control, which were lower than the 1.5X cake. Following the final application of inorganic

fertilizer (36 WAS), harvest quality ratings were not different between the 1.0X cake and the

inorganic fertilizer control, which was lower than the 1.5X cake treatment. Only the 1.0X, 1.5X

cake biosolids and the inorganic fertilizer control had acceptable quality ratings at harvest.

Similar to the previous year, the 1.0X cake biosolids treatment and inorganic fertilizer

control had similar quality ratings at harvest. The inorganic ratings were barely acceptable,

which was not the case in years one and two. The lower quality ratings can most likely be

attributed to the altered fertilization schedule. The last fertilization did not occur until the first

week of July and the turfgrass may have already been under heat stress and not able to efficiently

use the available nitrogen. The lower nitrogen uptake of the inorganic fertilizer treatment at

harvest in year three supports this conclusion. These results suggest there could be a non-

37

nutritive benefit to using biosolids during times of plant stress as reported by Zhang et al. (2009).

The results from year three still support the conclusion that there is a PAN and turfgrass N need

synchrony issue with the blended biosolids treatments.

Quality ratings combine color, density and texture of a turfgrass stand into one rating.

The below acceptable quality ratings measured in our study with the blended biosolids

treatments and the 0.5X cake biosolids treatment are attributed to poor stand density. In year

three, the lower quality ratings for the inorganic fertilizer control was attributed to poor color.

Because of the altered fertilization schedule, the inorganic fertilizer plots were slightly yellow at

harvest. The 1.0X cake biosolids quality ratings at harvest were acceptable each year, but usually

lower than the inorganic fertilizer control. Although the color ratings were acceptable, the lower

quality ratings with this treatment were attributed to lower density than the 1.5X cake biosolids

and inorganic fertilizer control treatments.

Limited research has investigated turfgrass quality during the growing season using non-

composted biosolids, but previous research on composted biosolids plus inorganic fertilizer

demonstrate increased turfgrass quality compared to using inorganic fertilizer alone

(Loschinkohl and Boehm, 2001; Schnell et al., 2009; Garling and Boehm, 2001). Tesfamariam et

al. (2009) showed increased turfgrass quality with increasing rates of anaerobically digested

biosolids. The biggest concern with using anaerobically digested biosolids to produce sod is

matching the estimation of PAN to the actual mineralization rate throughout the growing season.

Our quality results support the conclusion that the use of 30% organic nitrogen mineralization in

the first year overestimated the PAN of the cake biosolids.

3.4.6. Weed and Disease Pressure

38

There were no differences in weed pressure among treatments all three years of the study

(data not shown). Percent weed coverage was determined in mid-April each year and plots were

treated with herbicide after measurements were made. Significant weed populations were not

present at harvest each year. Previous research has shown that composted biosolids mulches can

suppress weeds (Persyn et al., 2007; Roe et al., 1993; Stoffella et al., 2000), but when biosolids

are incorporated the suppression effects diminish (Persyn et al., 2007). In turfgrass establishment

settings on disturbed soils, Dunifon et al. (2011) saw that a one-time compost blanket did not

suppress broadleaf weed coverage, but Linde and Hepner (2005) reported weed suppression

when plots were amended with composted biosolids compared to plots that only received

inorganic fertilizer. They attributed the suppression to the greater availability of N in biosolids

amended plots allowing the turfgrass to out-compete weeds.

Disease ratings were taken every two weeks when active disease was noticed at the study

site. The only disease that was rated during the study was brown patch (Rhizoctonia solani

Kühn). There were no differences in disease pressure among treatments all three years of the

study and disease symptoms were not evident at harvest (data not shown). Our results differed

from previous studies that reported disease suppression effects when using organic amendments.

Craft and Nelson (1996) reported Pythium root rot (Pythium spp.) suppression when seeding

turfgrass into biosolids amended root zones. Topdressing with compost has been reported to

suppress dollar spot (Sclerotinia homoeocarpa Bennett) (Boulter et al., 1999, Nelson and Craft,

1992), brown patch (Nelson and Craft, 1991a) and red thread (Laetisaria fusiformis McAlpine)

(Nelson and Craft, 1991b). The mechanism of organic amendments suppressing disease is not

well understood, and in some cases may just be the result of an increase in available nutrients

39

promoting a healthier growing turfgrass that is more resistant to disease (Loschinkohl and

Boehm, 2001).

3.4.7. Turfgrass Clipping Yield

Clipping weights were taken in the spring when the turfgrass was actively growing

(Table 3.7). Each clipping yield represents one week of growth. Clipping yields were taken

monthly until harvest. There were only two measurement dates for clipping yields in year one

due to delayed germination from lack of fall moisture. At 36 and 40 WAS, there were no

differences among the 1.5X cake and blended biosolids clipping yields compared to the

inorganic fertilizer control. There were no differences among the 1.0X and 1.5X cake biosolids

treatments and the inorganic fertilizer control at 32 WAS and 36 WAS in year two. At 40 WAS

there were no differences among the 1.0X and 1.5X cake, the 1.5X blended and the inorganic

fertilizer control. There were no differences among the 0.5X and 1.0X cake biosolids, the 0.5X

and 1.5X blended biosolids, and the inorganic fertilizer control at 32 WAS in year three. The

1.5X cake biosolids treatment had higher yields and the 1.0X blended biosolids treatment had

lower yields than the inorganic fertilizer control. There were no differences among the 0.5X and

1.0X cake biosolids, the blended biosolids, and the inorganic fertilizer control at 36 and 40

WAS. The 1.5X cake biosolids treatment had higher yields than the inorganic fertilizer control.

The results in year three differed from previous years, likely because the delayed seeding altered

the inorganic fertilization schedule. The fertilizer treatment should have received two

applications in the fall and one in the spring, but there was only one fall application and two in

the spring in year three. The last spring application was not efficiently utilized by the turfgrass

as indicated by the nitrogen uptake, quality and clipping yield results (Table 3.5, Table 3.6, Table

3.7).

40

Similar clipping yields between the inorganic fertilizer control and the 1.5X cake

biosolids treatment indicate that excessive growth would not occur. Overall, the results support

our previous conclusions that the 1.5X cake biosolids treatment is providing enough PAN to

support similar turfgrass growth compared to the inorganic fertilizer control. The results also

indicate that the 1.0X cake biosolids clipping yields were lower than the inorganic fertilizer

control, supporting the conclusion that 30% mineralization overestimates the amount of PAN of

the cake biosolids material. Supplemental nitrogen could increase the yields of the treatment and

allow for a quicker sod harvest cycle.

Previous research has attributed better turfgrass growth to improved soil conditions, such

as decreased bulk density, more plant available nutrients and increased water holding capacity,

from the application of composted biosolids (Cheng et al., 2007; Johnson et al., 2006;

Landschoot and McNitt, 1994). Research has also shown, through increased clipping yields, that

composted biosolids complemented inorganic fertilizer sources to produce faster establishment

of turfgrass (Loschinkohl and Boehm, 2001; Garling and Boehm, 2001). We did not measure

increased turfgrass growth from the use of anaerobically digested biosolids when compared to

inorganic fertilizer.

3.4.8. Sod Tensile Strength

Without adequate tensile strength, sod cannot be lifted at harvest. Tensile strength in year

one was determined on sod harvested at a 2.5 cm depth, deeper than the typical 1.2 to 1.9 cm

harvest depth. We harvested the sod at this depth because of delayed fall germination and

suspected handling issues at harvest. All biosolids treatments had lower tensile strength than the

inorganic fertilizer control in year one (Table 3.8).

41

The harvest depth for years two and three was 1.9 cm, and although slightly deeper than

typical, it was necessary to ensure that the sod held together during harvest. In year two, there

were no differences among the 0.5X and 1.0X cake biosolids, the 0.5X and 1.5X blended

biosolids, and the inorganic fertilizer control. The 1.5X cake biosolids had higher tensile strength

and the 1.0X blended biosolids treatment had lower tensile strength than the inorganic fertilizer

control. There were no differences in tensile strength among the 0.5X and 1.5X cake biosolids

treatments and the inorganic fertilizer control in year three. The trend of our tensile strength

measurements was similar to our establishment, quality ratings and clipping yields results.

Tensile strength increased with biosolids rate (Table 3.8). The higher tensile strength results in

year two suggest that application timing, longer production cycle and increased density has a

larger effect on tensile strength than increased harvest depth.

Tesfamariam et al. (2009) evaluated sod integrity as a percentage of harvestable sod. Sod

integrity is similar to sod tensile strength, but instead of measuring the actual force required to

break a piece of sod apart they measured how much of the sod in each plot could be handled

without breaking. They found that as biosolids rates increased from 0 to 100 Mg ha-1, sod

integrity increased up to the 33 Mg ha-1 rate and then declined as the rates continued to increase.

They attributed the decline in sod integrity to increased amounts of biosolids in the soil

decreasing the sod mass at harvest. At the 33 Mg ha-1 rate, the ratio of biosolids to soil increased

sod integrity, but as the ratio of biosolids to soil increased the turfgrass root system could not

bind as well to the soil/biosolids mixture. Flanagan et al. (1993) using the heavy fraction of

municipal solid waste, measured an increase in sod tensile strength as rates of heavy fraction

increased. They attributed the increase to improved media aeration. We measured a similar

42

response as Flanagan et al. (1993), i.e. tensile strength increased with higher rates of biosolids;

however, we attributed the increase to improved turfgrass density and root growth.

Previous research concluded that a minimum sod tensile strength of 196-215 Newtons

was needed so sod would not fall apart at harvest (Goatley and Schmidt, 1991; Flanagan et al.,

1993; Shearman et al., 2001). The minimum tensile strength seen in our study is lower than what

has been reported in previous literature. Tensile strengths less than 100 Newtons resulted in sod

that did not hold together well at harvest. Overall, the tensile strength results still support our

conclusion that the 1.5X cake biosolids treatment provided enough PAN during the production

cycle to produce an acceptable quality sod compared to the inorganic fertilizer control. The

results also indicate that 30% mineralization overestimates the amount of PAN of the cake

biosolids material and supplemental nitrogen is needed with the 1.0X cake biosolids treatment to

increase tensile strength to levels similar to the inorganic fertilizer control when using the current

estimates.

3.4.9. Transplant Rooting Strength

Transplant rooting strength indicates how well sod grows after it is harvested and

transplanted. When sod effectively roots at its establishment site, there is a lower chance that the

sod will die from stressful transplanting conditions like infrequent watering or poor fertilization.

In year one, there were no differences among the cake biosolids, the 1.5X blended

biosolids and the inorganic fertilizer control (Table 3.9). The 0.5X and 1.0X blended biosolids

had lower transplant rooting strengths than the inorganic fertilizer control. In years two and

three, there were no differences among any of the treatments.

Although only the 1.0X and 1.5X cake biosolids and the inorganic fertilizer control

produced an acceptable quality sod each year, all treatments had similar transplant rooting

43

strength. The sod was watered with 0.64 cm of water daily for a week after planting. The warm

soil temperatures in summer and the adequate water supply most likely allowed more nitrogen

from the biosolids to become plant available and promote adequate transplant rooting. All sod

pieces that were transplanted and grown for a month had above acceptable turfgrass quality (data

not shown).

The overall higher transplant rooting strengths measured in year one than in year two and

three are most likely due to the deeper harvest depth. It is possible that the additional initial root

mass and available nutrients in the sod pieces that were transplanted in year one promoted the

increase in rooting strength. Similar transplant rooting strength results that were seen in our

study were also seen by Flanagan et al. (1993) where there were no differences among treatments

that had heavy fraction applied and treatments with just topsoil. The inorganic fertilizer control

rooting strengths we measured are higher than previous studies that looked at transplant rooting

strength of Kentucky bluegrass (‘Georgtown’, ‘Plush’) and tall fescue (‘Rebel Jr.’) sod on the

same soil type at the Turfgrass Research Center in Blacksburg, VA (Goatley and Schmidt, 1991;

Zhang et al., 2003a; Zhang et al., 2003b). The higher rooting strengths may have occurred

because of higher rates of N used to establish and maintain the sod in our study (196 kg ha-1

compared to 100 kg ha-1) than in earlier studies. Our results indicate that the use of EQ biosolids

can result in the production of sod that transplants similar to inorganic fertilizer grown sod.

3.5. Conclusions

We determined that the EQ cake biosolids evaluated in this study, at the 1.0X and 1.5X

rates, can produce an acceptable quality sod comparable to sod grown with inorganic fertilizer.

The biosolids mineralization estimates used to recommend application rates underestimated the

PAN for both biosolids products as indicated by the lower nitrogen uptake throughout the

44

growing season and inadequate sod quality at harvest of the blended biosolids and the lower

although acceptable sod quality ratings at harvest of the cake biosolids compared to the inorganic

fertilizer control. We determined that there are no application uniformity issues when using the

cake or blended biosolids products, which is a concern during sod production due to the aesthetic

expectations of the crop. Also, biosolids use did not increase or suppress weed or disease

pressure, and as shown by the reduced N uptake in the inorganic fertilizer control in year three,

there may be non-nutritive benefits to using biosolids during times of plant stress. Sod growers

could use these alternative nutrient sources to reduce production costs without decreasing sod

quality. Sod production may provide another avenue for the beneficial use of biosolids.

3.6. Acknowledgements

The project site is on the grounds of Woodward Turf Farms, and we are thankful to Scott

Woodward for providing the field operation support for the research. We appreciate the field

assistance by Frederick ‘Dickie’ Shepherd, Jinling Li and Nathaniel Reams. We appreciate the

help of Steve Nagle for the lab work and instrumental analysis. We appreciate the Alexandria

Sanitation Authority for providing both biosolids products and Synagro, Inc. for the assistance

with transport and application of biosolids to the project site. This research was financially

supported by the United States Department of Agriculture Specialty Crop Research Initiative

(USDA SCRI).

45

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Zhang, X., E.H. Ervin and R.E. Schmidt. 2003a. Plant growth regulators can enhance the

recovery of Kentucky bluegrass sod from heat injury. Crop Sci. 43:952-956.

Zhang, X., E.H. Ervin and R.E. Schmidt. 2003b. Seaweed extract, humic acid, and

propiconazole improve tall fescue sod heat tolerance and posttransplant quality. Hort. Sci.

38:440-443.

Zhang, X., E.H. Ervin, G.K. Evanylo, and K.C. Haering. 2009. Impact of biosolids on hormone

metabolism in drought-stressed tall fescue. Crop Sci. 49:1893-1901.

49

Table 3.1 Average monthly temperature and precipitation for Remington, VA from August 2009 to August 20122009 Jan. Feb. Mar. Apr. May Jun. Jul Aug. Sept. Oct. Nov. Dec.

Temperature (°C) -- -- -- -- -- -- -- 25.8 20.2 13.6 9.9 1.8Precipitation (cm) -- -- -- -- -- -- -- 7.0 4.6 14.5 9.4 15.2

2010 Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Nov. Dec.Temperature ( °C) 0.8 -0.6 9.7 15.2 19.4 24.9 26.4 25.0 21.8 14.4 7.9 -0.6Precipitation (cm) 5.1 11.8 8.5 3.3 13.8 3.3 10.6 11.2 15.6 6.0 6.4 3.7

2011 Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Nov. Dec.Temperature (°C) -1.1 3.4 6.8 14.1 19.1 23.8 27.2 24.6 20.6 12.8 9.5 5.3Precipitation (cm) 4.7 5.6 12.9 13.2 8.3 3.6 6.6 9.5 20.1 15.9 5.5 11.3

2012 Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Nov. Dec.Temperature ( °C) 3.2 5.0 12.4 12.3 20.3 22.2 27.0 25.1 -- -- -- --Precipitation (cm) 4.7 5.7 3.9 4.6 13.7 4.5 6.2 7.7 -- -- -- --

30 yr. Avg. Temp.§ 0.6 2.3 6.8 12.4 17.3 22.4 24.8 24.1 19.9 13.3 8.0 2.630 yr. Avg. Precip.§ 7.4 6.9 8.6 8.9 11.7 10.2 9.4 8.9 9.9 8.4 8.6 7.6

§30 yr. average for the region (1982-2012)

Table 3.2. Chemical and physical composition of the biosolids products

Treatment C:N C§ TKN NH4-N NO3-N Organic-N Total P Kg kg-1

Blended† 15 230 15.0 5.3 0.004 9.7 9.5 2.6

Cake†† 7 339 51.1 15.5 0.006 35.6 34.2 1.5† Anaerobically digested dewatered biosolids blended with wood fines.†† Anaerobically digested dewatered biosolids cake.§ All analysis was done by A&L Eastern Labs, Richmond, VA.

50

Table 3.3. Target and Mean Actual Estimated First Year Plant Available Nitrogen (PAN) Applied from Biosolids

Target PAN to Applied Actual Estimated PAN AppliedTreatment kg N ha-1

Fert. Control 196 196Cake 0.5X† 98 117§

Cake 1.0X 196 235Cake 1.5X 294 352Blended 0.5X†† 98 90Blended 1.0X 196 180Blended 1.5X 294 270† Anaerobically digested dewatered biosolids cake.†† Anaerobically digested dewatered biosolids blended with wood fines.§PAN based on 100% availability of NH4

+-N and 30% availability of organic-N applied.

51

Table 3.4. Tall fescue-Kentucky bluegrass cover during the establishment season as influenced by inorganic fertilizer and various levels of de-watered cake or blended biosolids in Remington, VA from 2009-2012

Year 1§ Year 2¶ Year 3¶¶

Weeks after Seeding (WAS) 7 9 11 13 4 6 8 5 22 28 34Treatment and Estimated PAN % Vegetative Cover††

Fert. Control (196 kg N ha-1) 11.3ab 42.3ab 82.2ab 87.1a 8.4a 65.8a 92.7abc 12.5a 66.0b 84.5ab 77.8abCake 0.5X (98 kg N ha-1) 10.3ab 35.1b 63.7d 64.3c 3.6b 53.4ab 88.7bc 13.6a 59.6b 70.5b 74.5bCake 1.0X (196 kg N ha-1) 9.8ab 40.0ab 73.9bc 78.2ab 3.4b 60.2ab 95.9ab 14.2a 64.6b 76.3b 79.6abCake 1.5X (294 kg N ha-1) 9.1b† 35.8b 76abc 78.4ab 5.0ab 64.2a 97.7a 15.3a 80.6a 93.6a 93.1aBlended 0.5X (98 kg N ha-1) 10.7ab 40.3ab 69.6cd 71.1bc 4.4b 49.5b 85.1c 12.6a 33.0c 39.2d 40.5cBlended 1.0X (196 kg N ha-1) 11.2ab 41.1ab 72.5cd 72.8bc 4.6b 57.0ab 89.9bc 13.9a 36.4c 49.8cd 47.8cBlended 1.5X (294 kg N ha-1) 13.0a 48.2a 84.5a 86.4a 6.6ab 64.4a 94.7ab 13.7a 42.6c 55.1c 54.0cLSD (P 3.6 8.5 9.5 9.6 3.6 13.6 7.7 3.9 13.0 14.5 15.6†Means followed by the same letter are not significantly††Establishment coverage was determined using digital image analysis (DIA).§Actual rating dates in 2009 were Oct. 27, Nov. 10, Nov. 24 and Dec. 1.¶Actual rating dates in 2010 were Oct. 12, Oct. 26 and Nov. 8.¶¶ Actual rating dates in 2011 were Nov. 17 and in 2012 Mar. 15, Apr. 12 and May 24.

52

Table 3.5 Nitrogen uptake of tall fescue-Kentucky bluegrass sod during the growing season in Remington, VA from 2009-2012Year 1§ Year 2¶ Year 3¶¶

Weeks After Seeding (WAS) 36 40†† 32 36 40†† 32 36 40††

Treatment and Estimated PAN N Uptake† (kg N ha-1)Fert. Control (196 kg N ha-1) 24.9a 28.9a 9.2a 15.5a 13.9a 6.0b 5.4b 16.6bcdCake 0.5X (98 kg N ha-1) 3.7c# 7.0c 1.3bc 6.2bc 4.1bc 4.2b 3.9b 20.0bcCake 1.0X (196 kg N ha-1) 8.4bc 11.3bc 6.6ab 11.4ab 8.6abc 6.2b 13.4a 28.7abCake 1.5X (294 kg N ha-1) 15.2b 21.6ab 10.5a 17.5a 12.0a 16.6a 19.5a 41.4aBlended 0.5X (98 kg N ha-1) 1.4c 3.1c 0.3c 1.3c 2.6c 1.0b 0.7b 5.4dBlended 1.0X (196 kg N ha-1) 2.1c 6.5c 0.3c 1.3c 2.5c 0.8b 0.7b 8.4cdBlended 1.5X (294 kg N ha-1) 12.0b 13.3bc 1.8bc 4.0c 9.1ab 2.0b 0.8b 9.5cdLSD (P< 0.05) 7.8 10.8 5.4 6.1 6.4 5.2 7.8 14.1# Means followed by the same letter are not .† Calculated by multiplying turfgrass tissue N concentration (g N kg-1) by dry mass clipping yield (kg ha-1) for each treatment.††Sod was harvested at 40 WAS.§ Actual sampling dates in 2010 were May 18 and Jun. 15.¶ Actual sampling dates in 2011 were May 6, Jun. 3, and Jul. 1.¶¶ Actual sampling dates in 2012 were Jun. 22, Jul. 20 and Aug. 17.

53

Table 3.6. Tall fescue-Kentucky bluegrass sod turfgrass quality during the growing season in Remington, VA from 2009-2012Year 1§ Year 2¶ Year 3¶¶

Weeks After Seeding (WAS) 28 32 36 40†† 28 32 36 40†† 28 32 36 40††

Treatment and Estimated PAN Quality Rating† (1-9)Fert. Control (196 kg N ha-1) 5.8ab 8.0a 8.4a 7.8a 3.8b 6.5a 7.8a 7.3ab 5.1a 6.1a 6.0bc 6.6bCake 0.5X (98 kg N ha-1) 5.0bc 5.9b 5.9c 5.5bc 2.9cd 4.8b 5.3bc 5.1c 4.3b 4.8bc 5.3c 5.3cCake 1.0X (196 kg N ha-1) 5.4bc 6.0b 6.1bc 6.0b 3.3c 4.9b 6.1b 6.5b 4.1b 4.9b 6.1b 6.4bCake 1.5X (294 kg N ha-1) 6.5a 7.8a 7.8a 7.3a 4.4a 6.5a 8.0a 8.0a 5.3a 6.9a 7.3a 7.6aBlended 0.5X (98 kg N ha-1) 4.5c# 5.4b 5.4c 4.9c 2.5d 3.0d 4.0d 4.0d 3.5c 3.8d 4.4d 4.5dBlended 1.0X (196 kg N ha-1) 5.1bc 6.1b 6.0bc 5.8bc 2.6d 3.4cd 4.5cd 4.5d 3.6c 4.0cd 4.3d 4.5dBlended 1.5X (294 kg N ha-1) 5.4bc 6.4b 6.8b 5.8bc 3.1c 4.5bc 5.6b 5.4c 3.5c 3.9d 4.4d 4.8cdLSD (P< 0.05) 0.9 1.3 0.8 0.9 0.4 1.1 0.9 0.7 0.4 0.8 0.7 0.7

†Index scale is 1-9. 1 being brown grass and 6 being the minimal acceptable commercial quality rating.††Sod was harvested at 40 WAS.§ Actual sampling dates in 2010 were Mar. 23, Apr. 20, May 18 and Jun. 15.¶ Actual sampling dates in 2011 were Apr. 8, May 6, Jun. 3, and Jul. 1.¶¶ Actual sampling dates in 2012 were May 25, Jun. 22, Jul. 20 and Aug. 17.

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Table 3.7. Tall fescue-Kentucky bluegrass clipping yields during the growing season in Remington, VA from 2009-2012Year 1§ Year 2¶ Year 3¶¶

Weeks After Seeding (WAS) 36 40†† 32 36 40†† 32 36 40††

Treatment and Estimated PAN Clipping Yields† (kg ha-1)Fert. Control (196 kg N ha-1) 850.1a 1079.6a 324.7a 630.1a 445.5a 251.9bc 205.4bc 673.4bcCake 0.5X (98 kg N ha-1) 173.5cd# 340.0cd 60.9c 348.4bc 133.6bc 193.3cd 130.0c 694.7bcCake 1.0X (196 kg N ha-1) 387.1bc 590.7bcd 243.1ab 562.3ab 301.7ab 265.5b 389.9ab 900.2abCake 1.5X (294 kg N ha-1) 626.4ab 950.9ab 365.5a 728.2a 381.4ab 607.2a 561.1a 1303.2aBlended 0.5X (98 kg N ha-1) 75.0d 177.7d 20.2c 66.4d 88.4c 52.6cd 36.1c 196.9cBlended 1.0X (196 kg N ha-1) 112.7cd 361.2cd 13.7c 71.4d 87.3c 39.4d 35.9c 330.9bcBlended 1.5X (294 kg N ha-1) 561.4ab 687.4abc 86.1bc 192.6cd 309.5ab 96.9bcd 35.0c 318.7bcLSD (P< 0.05) 305.8 453.1 159.9 262.3 209.5 205.3 216.4 461.2

†Data was collected after one week of growth when the slowest growing plot reach a 10 cm height.††Sod was harvested at 40 WAS.§ Actual sampling dates in 2010 were May 18 and Jun. 15.¶ Actual sampling dates in 2011 were May 6, Jun. 3, and Jul. 1.¶¶ Actual sampling dates in 2012 were Jun. 22, Jul. 20 and Aug. 17.

55

Table 3.8. Tall Fescue-Kentucky bluegrass sod tensile strength at harvest in Remington, VA from 2010-2012


Treatment and Estimated PAN Newtons† (N)Fert. Control (196 kg N ha-1) 164.3a 187.6bc 118.9aCake 0.5X (98 kg N ha-1) 94.4cd# 182.7bcd 101.7aCake 1.0X (196 kg N ha-1) 98.1cd 196.1ab 78.5bCake 1.5X(294 kg N ha-1) 111.6bc 220.7a 105.4aBlended 0.5X (98 kg N ha-1) 84.6d 165.5cd 68.6bBlended 1.0X (196 kg N ha-1) 80.9d 154.5d 39.2cBlended 1.5X (294 kg N ha-1) 127.5b 166.7bcd 78.5bLSD (P< 0.05) 25.2 30.0 18.4

†Tensile strength was measured on three 91cm x 61cm pieces on sod from each plot at harvest.§ Harvest date was Jun. 15 in 2010.¶ Harvest date was Jul. 1 in 2011.¶¶ Harvest date was Aug. 17 in 2012.

Table 3.9. Tall fescue-Kentucky bluegrass sod transplant rooting strength four weeks after transplant from 2010-2012


Treatment and Estimated PAN Newtons† (N)Fert. Control (196 kg N ha-1) 750.2ab 360.4ab 453.3abCake 0.5X (98 kg N ha-1) 610.5abc 517.8a 547.6aCake 1.0X (196 kg N ha-1) 693.8abc 384.9ab 411.0abCake 1.5X (294 kg N ha-1) 890.0a 413.4ab 513.6aBlended 0.5X (98 kg N ha-1) 414.3c 387.4ab 425.5abBlended 1.0X (196 kg N ha-1) 436.4c 476.6a 514.2aBlended 1.5X (294 kg N ha-1) 475.6bc 266.3b 333.6bLSD (P< 0.05) 291.1 160.0 152.6# Means followed by the same letter are not †Three pieces of 30 cm x 30 cm sod were placed on rooting frames and allowed to establish for four weeks after transplant§ Transplant date was Jun. 15 in 2010.¶ Transplant date was Jul. 1 in 2011.¶¶ Transplant date was Aug. 17 in 2012.

56

4. The Effects of Land Applying Biosolids for Sod Production on Soil

Chemical and Physical Properties and Soil Loss at Harvest

J. Derik Cataldi*, Gregory K. Evanylo, and Erik H. Ervin

Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and

State University, Blacksburg, VA 24061

*Corresponding author ([email protected])

57

4.1. Abstract

Regulated application rates of biosolids products for sod production are required to be

based on crop N needs; however, the removal of nutrients (esp., N and P) and organic matter

with sod may warrant higher than agronomic N rate applications. The objective of this study was

to compare various application rates two types of biosolids products that may be suitable for sod

production. Exceptional Quality (EQ) products derived from anaerobically digested biosolids

were compared with an inorganic fertilizer control for sod fertilization on 1) the amount of soil,

C and P exported at harvest and 2) chemical and physical properties of the soil following sod

harvest as indicators of the benefits of biosolids use. The study was conducted on a sod farm in

Remington, Virginia on a silt loam Ashburn-Dulles complex from 2009 to 2012. The biosolids

products were applied at estimated plant available nitrogen (PAN) rates of 98 kg ha-1 (0.5X), 196

kg ha-1 (1.0X), 294 kg ha-1 (1.5X) for a tall fescue (Festuca arundinacea Schreb. ‘Rebel Exeda’,

‘Rebel IV’ and ‘Justice’) Kentucky bluegrass (Poa pratensis L. ‘Midnight’) mixture (85/15 % by

weight) and plots were seeded at 236 kg ha-1. One biosolids product was a dewatered cake

applied at 15, 30.5 and 46 wet Mg ha-1. The second biosolids product was the same dewatered

cake blended with wood fines applied at 17, 34 and 51 wet Mg ha-1. The biosolids treatments

were compared to an inorganic fertilizer control that supplied 196 kg N ha-1 through three

applications over the production cycle. After repeat applications of biosolids, the 0.5X rates did

not increase soil extractable phosphorus, but the 1.0X rates steadily increased soil extractable

phosphorus. The 1.0X and 1.5X biosolids rates increased soil organic matter content, and only

the 1.5X rate of cake biosolids reduced soil bulk density and mineral matter export at harvest.

Our results indicate biosolids used as fertility sources and soil amendments for sod production

can maintain soil phosphorus at concentrations that preclude environmental impairment within

58

rotational sod production systems that rely on annual biosolids applications. Occasional

substitution of inorganic fertilizer without phosphorus can ensure that environmentally harmful

soil P concentrations do not accrue.

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4.2. Introduction

The rising prices of fertilizer and fuel have increased the cost of sod production (NASS,

USDA, 2011). Use of biosolids as a soil amendment and plant nutrient source may be a way to

reduce costs. Previous research has found that production systems that used biosolids were more

economically efficient due to reduced nutrient costs (Faust and Oberst, 1996; Soulsby et al.,

2002).

Lower production costs associated with biosolids use are not the only benefits sod

producers might incur. The use of biosolids could reduce the amount of soil and associated

nutrients exported at harvest. Soil export is a serious environmental and agronomic consequence

of sod production (Millar et al., 2010; Carr, 1996; Charbonneau, 2003). When biosolids were

topdressed or incorporated at rates that greatly exceed turfgrass nutritional needs, soil export at

harvest was reduced (Tesfariam et al., 2009; Schnell et al., 2009). Although heavy rates can

reduce export, the effects of N based biosolids applications for sod production on soil export

need to be evaluated.

Biosolids could also help replace organic matter. The addition of organic residuals has

been shown to increase soil organic matter and available nutrients and reduce bulk density (Dai

et al., 2009; Brown and Cotton, 2011; Dunifon et al., 2011; Hepperly et al., 2009; Norrie and

Gosselin, 1996; Tambone et al., 2007; Evanylo et al., 2008; Bulluck III et al., 2002).

Applications of biosolids for turfgrass production were reported to have similar results (Schnell

et al., 2009; Johnson et al., 2006; Loschinkohl and Boehm, 2001). Long-term maintenance of

turfgrass systems naturally result in soil organic matter deposition (Qian and Follet, 2002), but

there have been conflicting reports on whether or not sod production increases or diminishes soil

organic matter (Carr, 1996; Sheard and Van Patter, 1978; Charbonneau, 2003; Skogley and

60

Hesseltine, 1978; Millar et al., 2010). Although previous studies have reported that biosolids

applications increased soil organic matter in turfgrass culture, more research is needed to

determine if N-based rates will increase soil organic matter in a sod production system.

Because of the imbalance in biosolids N and P, the application of biosolids to supply crop

nitrogen needs will result in the over application of phosphorus (Ott and Forster, 1978). The

continual application of organic residuals can cause excessive soil phosphorus accumulation to

impair surface water quality as P transport occurs (Richards et al., 2008; Whalen and Chang,

2001; Rostagno and Sosebee, 2001; Korboulewsky et al., 2002; Shober and Sims, 2003).

Excessive soil phosphorus accumulation in production fields could be reduced by standard sod

harvest as sod production exports nutrients through sod harvest (Vietor et al., 2004; Richards et

al., 2008; Tesfariam et al., 2009; Schnell et al., 2009).

Alternative processing methods that produce EQ (USEPA, 1993) products are constantly

being developed. These products can be used in urban settings because of their low pollutant

concentrations and pathogen-free status. They are usually composted, have higher C:N ratios and

lower moisture contents which make them easier to handle. The need for bulking agents during

composting allows for beneficial use of lower value waste products (e.g., yard-waste or

municipal solid waste) in these higher value EQ products (Beecher and Goldstein, 2010).

Typically inorganic fertilizer is used in conjunction with these products because of their low

amounts of PAN (Loschinkohl and Boehm, 2001). Previous research in turfgrass culture has

shown that these products enhance turfgrass establishment and quality more than inorganic

fertilizer alone and can increase surface soil organic matter as well (Schnell et al., 2009;

Loschinkohl and Boehm, 2001; Linde and Hepner, 2005; Landschoot and McNitt, 1994).

Understanding the value of such products (e.g., the effects on soil chemical and physical

61

properties, nutrient availability) will enable their promotion for sod production. Nitrogen

availability of digested, dewatered cake biosolids have been previously studied (Gilmour et al.,

2003), but little is known about nitrogen availability of non-composted woody blended biosolids

products.

The objective of this study was to compare processing methods and application rates of

anaerobically digested biosolids products with an inorganic fertilizer control for sod fertilization

on 1) the amount of soil, C and P exported at harvest and 2) chemical and physical properties of

the soil following sod harvest as indicators of the benefits of biosolids use.

4.3. Materials and Methods

Site, experimental design, and treatment establishment

The study was conducted on a sod farm in Remington, VA (Lat. +38.51417, Long. -

77.811717) on a silt-loam Ashburn-Dulles complex (Fine-silty, mixed, active, mesic Oxyaquic

Hapludalfs). The study was conducted from the fall of 2009 until the summer of 2012. Mean

monthly temperature and precipitation for the duration of the study were obtained from nearby

weather stations (NOAA, 2013).

The study consisted of seven treatments, each replicated 4X and arranged in a

randomized complete block design. The treatments included three rates (0.5X, 1.0X and 1.5X

agronomic N rate) of each of two types of biosolids and a fertilizer control, according to Virginia

Tech Soil Testing Laboratory recommendations (Donohue and Heckendorn, 1994). The 0.5X,

1.0X, and 1.5X treatments were designed to apply 98 kg ha-1, 196 kg ha-1, and 294 kg ha-1 of

plant available nitrogen (PAN), respectively. Plot dimensions were 61 m by 11 m, which

necessitated biosolids applications made using a commercial side-discharge manure spreader.

62

An EQ anaerobically digested, dewatered biosolids cake (Alexandria Sanitation

Authority, Alexandria, VA) and the same material blended with wood fines (blended by

Synagro, Inc., Champlain, VA) at a 1:0.65 by weight ratio of biosolids to wood fines were used.

Biosolids were applied in the fall (Aug. 26, 2009, Sept. 8, 2010, and Oct. 12, 2011) of each year

based on their estimated supply of plant available nitrogen assuming 30% of the organic nitrogen

is mineralized in the first year (Virginia Department of Conservation and Recreation, 2005).

Although the organic nitrogen content and application rate of the biosolids varied slightly from

year to year the three-year mean biosolids rates were 15, 30.5 and 46 wet Mg ha-1 of cake

biosolids, respectively, and 17, 34 and 51 wet Mg ha-1 of blended biosolids, respectively. The

inorganic fertilizer control treatment supplied 196 kg N ha-1, whose application was split to

provide 74 kg N ha-1 (as urea and diammonium phosphate, DAP) at seeding, 74 kg N ha-1 (as

calcium ammonium nitrate) in mid-October, and 48 kg N ha-1 (as calcium ammonium nitrate) in

late-April. The DAP rate was calculated to meet the soil test recommended amount of

phosphorus and incorporated to a depth of five cm.

Samples from each biosolids source were collected at application dates and sent to A&L

Eastern Laboratories in Richmond, VA and analyzed for total solids (SM-2540G), total Kjeldahl

N (SM-4500- TKN), ammonium-N (SM-4500-NH3) (Standard Methods for the Examination of

Water and Wastewater, 1992), phosphorus (SW-846-6010C), potassium (SW-846-6010C) (U.S.

Environmental Protection Agency, 1986), and other macro and micro nutrients. The cake

biosolids was composed of 339 g kg-1 C, 5l.1 g kg-1 TKN, 35.6 g kg-1 P, 1.5 g kg-1 K and had a

moisture content around 700 g kg-1. The blended biosolids were composed of 230 g kg-1 C, 15.0

g kg-1 TKN, 9.7 g kg-1 P, 2.6 g kg-1 K and had a moisture content ~300 g kg-1. The 0.5X, 1.0X

and 1.5X cake biosolids rates applied 117, 235 and 352 kg of estimated PAN ha-1 respectively;

63

154, 308 and 462 kg P ha-1 respectively; and 1,525, 3,051, and 4,576 kg C ha-1 respectively. The

0.5X, 1.0X and 1.5X blended biosolids rates applied 90, 180 and 270 kg of estimated PAN ha-1

respectively; 105, 210 and 315 kg P ha-1 respectively; and 2,530, 5,060, and 7,820 kg C ha-1

respectively.

All plots were seeded with a Brillion Turfmaker (Brillion Farm Equipment, Brillion, WI)

at 236 kg ha-1 with an 85% tall fescue (Festuca arundinacea Schreb. ‘Rebel Exeda’ ‘Rebel IV’

and ‘Justice’)/ 15% Kentucky bluegrass (Poa pratensis L. ‘Midnight’) mixture, by weight. Plots

were seeded Sept. 2 in 2009; Sept. 14 in 2010; Oct. 12 in 2011. Plots were maintained at a 7.6

cm height throughout the growing season and clippings were returned.

Sampling and analysis

In the fall of 2009 soil cores with a 1.9 cm diameter were randomly collected from the 0-

10 cm depth in the study site, air-dried, ground to pass through a 2 mm sieve and sent to Virginia

Tech Soil Testing Laboratory for routine soil test analysis of Mehlich 1 extractable P, K, and pH

and Walkley-Black soil organic matter content (Maguire and Heckendorn, 2011). Results

indicated a pH of 6.1, extractable P and K of 12 mg kg-1 and 43 mg kg-1 respectively and soil

organic matter content of 32 mg kg-1. Fertilizer P recommendations for the inorganic fertilizer

control plots and K recommendations for all treatments were made using soil testing results

(Virginia Department of Conservation and Recreation, 2005).

Soil extractable phosphorus was measured in each plot before initial treatments and after

each sod harvest. Soil cores with a 1.9 cm diameter were randomly collected from the 0-10 cm

depth in each plot, air-dried, ground to pass through a 2 mm sieve and sent to Virginia Tech Soil

Testing Laboratory for analysis of Mehlich 1 extractable P (Maguire and Heckendorn, 2011).

64

Organic matter to a depth of 10 cm was measured for each plot before initial treatments

and after each sod harvest. Organic matter was determined using soil cores with a 1.9 cm

diameter that were randomly collected from the 0-10 cm depth in each plot, air-dried, ground to

pass through a 2 mm sieve and sent to Virginia Tech Soil Testing Laboratory for analysis of

Walkley-Black soil organic matter content (Maguire and Heckendorn, 2011). Bulk density was

measured by taking five 81 cm2 plugs with a standard golf course cup cutter, saving the removed

soil, lining the hole with plastic and recording volume of water required to fill the hole. The

saved soil was dried to a constant weight at 60°C and weighed. The weight of soil in grams was

divided by the volume of water required to fill the hole to give bulk density in g cm3-1 (Blake and

Hartge, 1986).

The amount of mineral matter exported at harvest was quantified using physical plant-soil

separation. Four sod pieces, 91 cm by 61 cm were randomly harvested from three locations in

each plot. One 81 cm2 plug was taken from each piece of sod using a standard golf course cup

cutter. The plugs were dried at 60°C for several days before the plant tissue was removed. The

plant tissue was removed by grinding the samples with a mortar and pestle to loosen the soil.

Mineral matter export was determined by weighing the separated soil after it was ignited in a

Blue M Ultra-Temp, forced-air drying oven (SPX Thermal Products Solutions, White Deer, PA)

for 6 hours at 500°C.

Soil extractable phosphorus, organic matter, bulk density and mineral matter export data

were subjected to analysis of variance using SAS Proc GLM (SAS Institute, 2008) to elucidate

the effects of organic soil amendments on soil chemical and physical properties. Means were

separated using a Protected LSD at P

65

4.4. Results and Discussion

There were significant year by treatment interactions for the extractable phosphorus and

soil loss data, so each year is presented separately. There was no significant year by treatment

interactions for the organic matter and bulk density data, so the averages over the three year

study are presented.

4.4.1. Biosolids composition and application rates of N, P, K and C

Biosolids composition and application rates of N, P, K and C are shown in Tables 4.1 and

4.2. The amounts of C, TKN, NH4+-N, organic-N and P were lower in the blended biosolids than

in the cake biosolids. The only nutrient that was higher in the blended biosolids was K. The

additional processing the blended biosolids underwent caused a reduction in the amount of

ammonia nitrogen and organic nitrogen resulting in a product with a C:N ratio of 15:1 as

compared to 7:1 of the cake biosolids.

The amount of total P that was applied from each nutrient source is shown in Table 4.2.

The 0.5X levels of cake and blended biosolids provided similar total P as the inorganic fertilizer

control. Results from the 0.5X treatments can be used to demonstrate the effects of phosphorus-

based biosolids rates on soil chemical and physical properties.

4.4.2. Soil extractable phosphorus accumulation

After harvest in year one, the 1.0X and 1.5X blended biosolids treatments resulted in

greater soil extractable phosphorus than the inorganic fertilizer control (Table 4.3). After year

two harvest, all of the biosolids treatments except the 0.5X cake treatment resulted in greater soil

extractable phosphorus than the inorganic fertilizer control. After year three harvest, only the

0.5X cake and blended biosolids treatments did not have higher soil extractable phosphorus than

the inorganic fertilizer control.

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Previous research has shown that repeat applications of biosolids at N based rates and

above can increase soil phosphorus (Kelling et al., 1977; Chang et al., 1983; Maguire et al.,

2000). Sod production may counteract the accumulation of phosphorus in the soil from repeat

biosolids applications. Previous research has reported that sod production can export nutrients

and the amount exported is dependent on the amount of nutrients applied, incorporation method

and harvest depth (Vietor et al., 2002; Schnell et al., 2009; Tesfariam et al., 2009). Vietor et al.

(2002) and Schnell et al. (2009) reported that the amount of phosphorus exported at sod harvest

increases when more phosphorus is applied, and concluded that more phosphorus is exported

when organic amendments are topdressed instead of incorporated. When organic amendments

were topdressed and harvested at a 2.5 cm depth, Vietor et al. (2002), reported that 77% of

phosphorus applied was exported with the sod. Schnell et al. (2009) reported that all of the

phosphorus from a 46 dry Mg biosolids ha-1 application that was incorporated to a 5 cm depth

was removed from consecutive sod harvests of 2 and 2.7 cm depths. Tesfariam et al. (2009) did

not measure an increase in surface soil phosphorus to a 15 cm depth until biosolids were

topdressed at 33 dry Mg ha-1.

Initial soil test phosphorus at the study site was 12 mg kg-1. Based on soil test

recommendations, we applied 86 kg ha-1 each year to our inorganic fertilizer treatment plots. The

biosolids supplied 154, 308, and 462 kg P ha-1 with the 0.5X, 1.0X and 1.5X cake rates,

respectively, and 105, 210, and 315 kg P ha-1 with the 0.5X, 1.0X, and 1.5X blended rates,

respectively. Although the 1.0X and 1.5X biosolids rates supplied more than two and three times,

respectively, more phosphorus than the soil test recommendations, the increases in soil

extractable phosphorus after three years would not have prohibited further use of biosolids for

sod production. For sod production in Virginia, phosphorus applications are recommended when

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Mehlich I soil extractable phosphorus levels are below 55 mg kg-1 (Virginia Department of

Conservation and Recreation, 2005). Our extractable phosphorus results indicate that N-based

rates of biosolids can be used in consecutive years without excessive increases in soil extractable

phosphorus. To implement a biosolids-based sod production system, growers would likely need

to adopt a rotational system where biosolids would be used for several years at N-based rates

before switching to an inorganic fertilizer system with no phosphorus inputs to deplete the

accumulated soil phosphorus. This period of permissible biosolids application will be lower in

sod production systems due to the removal of phosphorus with the sod.

4.4.3. Soil organic matter accumulation and soil bulk density

After applying the biosolids treatments for three years, the 1.0X and 1.5X cake and

blended biosolids treatments increased organic matter compared to the inorganic fertilizer

control (Table 4.4). The 1.5X blended biosolids treatment increased organic matter more than

any other treatment. Only the 1.5X cake biosolids treatment decreased soil bulk density

compared to the inorganic fertilizer control.

Long-term turfgrass systems increase soil organic matter because of the high root turn-

over and low soil disturbance (Qian and Follet, 2002). Sheard and Van Patter (1978) and

Skogley and Hesseltine (1978) reported sod production maintains and possibly increases soil

organic matter. They concluded that organic matter depletion does not occur because of the

dense root system that is left behind after sod harvest. Skogley and Hesseltine (1978) estimated

that about 9 Mg ha-1 yr-1 of organic matter is added to soil in sod production.

In traditional agricultural crop production, organic matter increases with the addition of

organic amendments has been reported (Khaleel et al., 1981). Johnson et al. (2006) reported that

topdressing composted organic amendments increased soil organic matter during turfgrass

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establishment, but there has been no research on the effects of organic amendments on soil

organic matter in sod production. Organic amendments are usually topdressed or surface applied

in turfgrass settings, but in sod production the beneficial effects of the amendment on soil

physical properties are not realized without incorporation below the sod harvest depth. Our

results indicate that soil organic matter can be increased more than with inorganic fertilizer given

that repeat applications of incorporated biosolids at N based rates are made.

Decreasing bulk density in sod production fields can improve turfgrass growth and

quality (Dunifon et al., 2011; Gaudreau et al., 2002; Johnson et al., 2006) and reduce the weight

of sod, which can reduce transport costs for producers. Khaleel et al. (1981) attributed the

decrease in bulk density with organic amendments to the dilution of heavier mineral component

of soil by the less dense organic matter. Both Schnell et al. (2009) and Tesfariam et al. (2009)

attributed reduced sod weight when high rates of biosolids were applied to reduced surface soil

bulk density. The effects of repeated N-based biosolids rates on bulk density in sod production

soils are not well known. The use of approximately N-based rates by Tesfariam et al. (2009) did

not reduce soil bulk density when biosolids were surface-applied. In our study, only the 1.5X

cake biosolids rate decreased bulk density. It remains to be seen how longer term annual

applications of agronomic N rates of biosolids would affect soil bulk density.

4.4.4. Mineral matter export

During the entire study, only the 1.5X cake biosolids had a positive effect on soil export,

reducing mineral matter export during harvest in years 1 and 3 and eliciting no difference in year

2 (Table 4.5).

A number of studies to quantify the amount of soil export with each sod harvest have

been completed since the late 1970’s. There have been conflicting reports as to whether or not

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mineral soil export during sod production is actually occurring (Carr, 1996; Sheard and Van

Patter, 1978; Charbonneau, 2003; Skogley and Hesseltine, 1978). Mineral soil export is difficult

to quantify because harvested sod consists of roots, rhizomes, organic matter and mineral soil

that are bound together in the sod pad. Overestimation of soil export occurs if the mineral

fractions from the roots, rhizomes and organic matter are included in the calculations (Sheard

and Van Patter, 1978; Skogley and Hesseltine, 1978).

Millar et al. (2010) reported that mineral soil export at harvest was between 74 and 114

Mg ha-1 each year, similar to the range of Skogley and Hesseltine (1978) at 61 to 105 Mg ha-1 at

a 1.25 cm harvest depth. In our study we were forced to use two distinct harvest depths based on

differences in crop development by ten months after seeding. In year one, to ensure that all of the

treatments would hold together, sod was harvested at a 2.5 cm harvest depth. This was lowered

to a 1.9 cm depth for years two and three. The inorganic fertilizer control in years two and three

exported between 149 and 224 Mg of mineral matter ha-1. We reported mineral matter removal to

account for the added mineral fraction of the biosolids.

We expected the amount of mineral matter exported to decrease with increasing rates of

biosolids. This did not always occur. A hypothesis that warrants further investigation as to why

we did not measure the expected trend is that there was harvest depth variability. The cutting

height was not changed from plot to plot, but the sod was not harvested as deep from plots that

were drier compared to wetter plots (Cataldi, personal observation).

Both Tesfariam et al. (2009) and Schnell et al. (2009) cited sod mass differences to

conclude that biosolids could reduce the export of soil during sod harvest by diluting the soil

surface with the organic amendment. Significant soil export reduction did not occur unless

biosolids rates of 33 to 100 dry Mg ha-1 were used (Tesfariam et al., 2009; Schnell et al., 2009).

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The only treatment in our study that reduced mineral matter export at harvest compared to the

inorganic fertilizer control was the 1.5X cake biosolids treatment. The range of mineral matter

export for this treatment was 143-177 Mg ha-1. The 1.5X cake rate applied 13.5 dry Mg biosolids

ha-1, which is less than the lowest rate reported to reduce soil export in Tesfariam et al. (2009).

We concluded that the 1.5X biosolids rate diluted the surface soil with less dense organic

material and also reduced mineral soil export. Although our 1.5X cake rate reduced mineral soil

export, our results indicate that the state allowable biosolids rate for sod production (1.0X) did

not reduce mineral soil export.

4.5. Conclusions

We determined that the cake and blended biosolids improved soil quality by increasing

soil organic matter. We also determined that repeat applications of low rates of biosolids did not

reduce bulk density in a sod production system. Biosolids can be used to reduce soil bulk density

by diluting the heavy native surface soil with less dense material. We determined that the lower

biosolids rates were not supplying enough material below the sod harvest depth to measurably

dilute the soil even though all treatments were incorporated to 5 cm. Mineral matter export at

harvest was reduced using the highest cake biosolids rates, indicating again that there was not

enough material being applied with the lower rates to dilute the surface soil and reduce the sod

mass exported as was reported in previous studies. These results indicate that sod growers that

use biosolids to produce sod not only get the benefit of reduced production costs, but will also

see soil quality improvements and will be able to consecutively use biosolids to supply all of the

crop N needs without increasing soil phosphorus above manageable levels.

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4.6. Acknowledgements

The project site is on the grounds of Woodward Turf Farms, and we are thankful to Scott

Woodward for providing the field operation support for the research. We appreciate the field

assistance by Frederick ‘Dickie’ Shepherd, Jinling Li and Nathaniel Reams. We appreciate the

help of Julia Burger, Steve Nagle and Jinling Li for the lab work and instrumental analysis. We

appreciate the Alexandria Sanitation Authority for providing both biosolids products and

Synagro, Inc. for the assistance with transport and application of biosolids to the project site.

This research was financially supported by the United States Department of Agriculture

Specialty Crop Research Initiative (USDA SCRI).

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Table 4.1. Chemical and physical composition of the biosolids products applied to the experiment(2009-2012)

Treatment C:N C§ TKN NH4-N NO3-N Organic-N Total P Kg kg-1

Blended† 15 230 15.0 5.3 0.004 9.7 9.5 2.6

Cake†† 7 339 51.1 15.5 0.006 35.6 34.2 1.5† Anaerobically digested dewatered biosolids blended with wood fines.†† Anaerobically digested dewatered biosolids cake.§ All analysis was done by A&L Eastern Labs, Richmond, VA.

Table 4.2. Annual application rates of biosolids on a dry weight basis and N,P,K and C to treatments in Remington, VA (2009-2011)

Rate N§ P K CTreatment and Estimated PAN Mg ha-1 kg ha-1

Fert Control (196 kg N ha-1) -- 196 86 140 --Cake 0.5X (98 kg N ha-1)† 4.5 230 154 147 1525Cake 1.0X (196 kg N ha-1) 9.0 460 308 154 3051Cake 1.5X (294 kg N ha-1) 13.5 690 462 161 4576Blended 0.5X (98 kg N ha-1)†† 11.0 165 105 169 2530Blended 1.0X (196 kg N ha-1) 22.0 330 210 198 5060Blended 1.5X (294 kg N ha-1) 34.0 510 315 227 7820† Anaerobically digested dewatered biosolids cake.†† Anaerobically digested dewatered biosolids blended with wood fines.§Based on TKN applied, plant available nitrogen rates are lower.

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Table 4.3. Mehlich I soil extractable phosphorus of the surface soil to a 0-10 cm depth in Remington, VA (2010-2012)


Treatment and Estimated PAN mg kg-1

Fert. control (196 kg N ha-1) 11.5c† 9.5e 11.3cCake 0.5X (98 kg N ha-1) 10.5c 11.5de 15.5cCake 1.0X (196 kg N ha-1) 12.8c 14.8b 24.8bCake 1.5X (294 kg N ha-1) 13.0c 15.8bc 33.0aBlended 0.5X (98 kg N ha-1) 11.8c 13.8cd 15.8cBlended 1.0X (196 kg N ha-1) 17.8b# 17.8b 23.0bBlended 1.5X (294 kg N ha-1) 25.3a 26.0a 33.0aLSD (P< 0.05) 3.4 3.2 6.5#†Soil extractable phosphorus was sampled after each harvest.§ Actual sample date was Jun. 15 in 2010.¶ Actual sample date was Jul. 1 in 2011.¶¶ Actual sample date was Aug. 17 in 2012.

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Table 4.4. Soil organic matter and bulk density averaged over three production cycles (2009-2012) Organic Matter† Bulk Density

Treatment and Estimated PAN g kg-1 g cm-3

Fert. Control (196 kg N ha-1) 29.8d 1.51aCake 0.5X (98 kg N ha-1) 30.8cd 1.53aCake 1.0X (196 kg N ha-1) 31.7bc 1.52aCake 1.5X (294 kg N ha-1) 32.7b# 1.42bBlended 0.5X (98 kg N ha-1) 30.7cd 1.54aBlended 1.0X (196 kg N ha-1) 32.0bc 1.52aBlended 1.5X (294 kg N ha-1) 34.9a 1.48abLSD (P< 0.05) 1.6 0.07

#†Organic matter and bulk density values are averaged across the three years of the study.

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Table 4.5. Mineral matter export at harvest each year (2010-2012)Year 1† Year 2¶ Year 3¶¶

Treatment and Estimated PAN Mg ha-1

Fert. Control (196 kg N ha-1) 200a 149e 224aCake 0.5X (98 kg N ha-1) 169bc# 201ab 228aCake 1.0X (196 kg N ha-1) 191ab 181cd 220aCake 1.5X (294 kg N ha-1) 166c 143e 177bBlended 0.5X (98 kg N ha-1) 205a 217a 220aBlended 1.0X (196 kg N ha-1) 184abc 194bc 223aBlended 1.5X (294 kg N ha-1) 190ab 161de 200abLSD (P< 0.05) 23 20 31

#† Harvest depth was 2.54 cm. Harvest date was Jun. 15 in 2010.¶ Harvest depth was 1.9 cm. Harvest date was Jul. 1 in 2011.¶¶ Harvest date was Aug. 17 in 2012. Harvest depth was 1.9 cm.

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5. Conclusions

Application of organic amendments, particularly biosolids, can be used to establish and

maintain high quality stands of turfgrass. The application of organic amendments in turfgrass

settings can also improve soil quality by increasing soil organic matter, water retention and

decreasing bulk density. Biosolids have been used for sod production, but the focus of previous

studies has been to export nutrients/biosolids from sod production fields to establishment sites.

Because of this focus biosolids were applied at rates that exceeded crop nutritional needs. The

effects of N-based biosolids applications for sod production are not well known. This thesis

focused on the effects of N-based biosolids applications, from two EQ biosolids products, for sod

production on turfgrass establishment and quality as well as soil chemical and physical

properties. To accomplish this an experiment was designed to evaluate an EQ de-watered cake

biosolids and the same material blended with wood fines, for sod production on the

establishment, sod quality, sod tensile strength, sod transplant rooting strength, soil extractable

phosphorus, soil organic matter content and mineral matter export at harvest of a tall fescue-

Kentucky bluegrass sod.

To evaluate these effects we conducted a three-year field study in Remington, VA on a silt-

loam Ashburn-Dulles complex from 2009-2012. Overall our results indicated that current N

mineralization estimates of 30-35% worked well for the dewatered cake biosolids, but were too

high for the blended biosolids product. Sod properties, such as tensile strength and quality at

harvest were the same if not slightly higher with the 1.5X cake biosolids rate than the inorganic

fertilizer control. The 1.0X cake biosolids was the only other biosolids rate to produce an

acceptable quality sod, but slightly lower quality ratings and tensile strength seen in our study

suggest that the treatment would benefit from a spring application of supplemental nitrogen.

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We also saw that the 1.0X and 1.5X of both biosolids products increased organic matter after

three years of applications, but only the highest rate of cake biosolids reduced bulk density.

These results indicate that incorporation of N based biosolids rates can still apply enough organic

matter to increase soil organic matter and slightly improve soil quality even after sod harvest.

Even with our deeper harvest depths and lower application rates than previous studies, we saw an

accumulation of P in the surface 10 cm of soil with biosolids rates higher than 0.5X. These

results suggest and support other researcher’s conclusions that nutrient export of incorporated

biosolids is less than topdressed or unincorporated biosolids applications. Also, our results

indicate that incorporated N based biosolids rates can reduce soil export at harvest, but only

when using the 1.5X cake biosolids rate.

These results could provide background information for turfgrass establishment and sod

production studies using alternative biosolids products in the state of Virginia. Future work

using biosolids for sod production should look at using synthetic netting to increase the tensile

strength of the sod and reduce the harvest depth. The shallower harvest depth will affect the

amount of nutrients exported from the production field and could ultimately lead to faster

increases in soil phosphorus, but it would more accurately reflect the sod production industry in

the state. Also, a better quantification of soil export when using biosolids is needed. The future

research will add to the knowledge base and further refine the recommendations made when

using biosolids for sod production or in general turfgrass settings.

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